Bonding compositions for dental use

ABSTRACT

An antibacterial bonding compositions for dental use, which comprises (A) an antibacterial primer that comprises an antibacterial polymerizable monomer having an ethylenic unsaturated group and at least one or more cationic groups selected from the group consisting of ammonium bases, pyridinium bases and phosphonium bases, and a volatile solvent, and (B) an adhesive composition comprising an acid group having polymerizable monomer, a polymerizable monomer, and a polymerization initiator; and an adhesive compositions for dental use, which comprises (P) an adhesive primer comprising an acid group having polymerizable monomer, a hydrophilic polymerizable monomer, and water, and (Q) a bonding agent comprising a polymerizable monomer, and an acylphosphine oxide compound and an α-diketone compound both serving as a polymerization initiator. The bonding compositions can inhibit the growth of cariogenic bacteria in the bonded area of a tooth as restored with a restorative dental material in dental treatment thereby preventing secondary caries and odontitis around that area, and can enhance the bonding strength, especially the bonding durability of the restorative dental material to the tooth.

This application is a Continuation of application Ser. No. 09/377,071filed on Aug. 19, 1999 now U.S. Pat. No. 6,355,764.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to bonding compositions suitable fordental use. More precisely, the invention relates to bondingcompositions suitable for dental use, which exhibit good adhesivenessbetween a tooth and restorative dental materials in dental treatment,and which are for preventing the growth of cariogenic bacteria in thebonded area.

2. Description of the Related Art

In dental treatment, where partial defects in teeth are restored throughprosthesis with restorative dental materials such as, for example,composite resins, monomers, metal alloys and ceramics for dentalrestoration, dental bonding compositions are often used. However, whensuch a restorative dental material is directly bonded to the surface ofa tooth, it does not exhibit satisfactory bonding strength since it isnot adhesive by itself. As a result, the restorative dental material asdirectly bonded to a tooth will peel off, or, as the case may be,bacteria will penetrate into the bonded interface between the tooth andthe restorative dental material to cause secondary caries and odontitis.

In order to solve this problem, various dental bonding methods whichinclude previous application of some tooth surface treating agents todefective teeth to be restored have heretofore been described. Somereports disclose that such tooth surface treating agents improve thebonding strength between a tooth having been pre-treated with any ofthem and a restorative dental material applied to the surface-treatedtooth. For example, (1) Journal of Dental Research Vol. 34, pp. 849-854,1955 discloses that some acid etching primers improve the bondingstrength of restorative dental materials to tooth enamel; (2) Journal ofDental Research, Vol. 63. pp. 1087-1089, 1984 discloses that a primercomposition comprising glutaraldehyde, 2-hydroxyethyl methacrylate(hereinafter referred to as HERA) and water enhances the bondingstrength of restorative dental materials to tooth; (3) JP-A-62-223289discloses that a primer as prepared by adding an acid such as maleicacid, nitric acid or p-toluenesulfonic acid to an aqueous solution ofHEMA improves the bonding strength of restorative dental materials totooth enamel and tooth; (4) JP-A-1-113057 discloses that a primer asprepared by adding a salt of an acid to an aqueous solution of HEMAimproves the bonding strength of restorative dental materials to toothenamel and tooth; and (5) Materials and Instruments for Dental Use, Vol.9. pp. 65-73, 1990 discloses that a primer as prepared by adding amonomer having an amino acid residue such as N-acryloylaniline or thelike to an aqueous solution of HEMA improves the bonding strength ofrestorative dental materials to tooth enamel and tooth. In addition, (6)JP-A-3-240712 discloses a dental bonding composition as prepared byadding a polymerizable monomer having an acidic group and a curing agentto an aqueous solution of HEMA; and (7) JP-A-4-8368 discloses thatadding an amino compound to the dental bonding composition in (6)enhances the ability of the composition to improve the bonding strengthof restorative dental materials to teeth.

In particular, a dental bonding method of using a self-etching adhesiveprimer is an extremely excellent technique, as being easy to perform andprovides a high bonding strength to the tooth. The adhesive primer foruse in the method comprises an acid (including acidic monomers), ahydrophilic monomer and water, and the method of using it comprisesapplying the primer to the surface of a tooth and directly applying abonding material thereto without washing and drying the primer-coatedtooth.

However, the self-etching adhesive primer which does not require washingwith water is problematic in that the polymerizable monomer will partlyremain in the surface layer of tooth even though most of the solventsuch as water and the like could be removed through drying with a dentalair syringe after its application. The remaining monomer may bepolymerized and cured together with the overlaid bonding material byirradiation of light. However, the adhesive primer contains lowpolymerizable monomers such as hydrophilic monomers and acidic monomers,which could not be polymerized all at once. In order to enhance itspolymerizability, some means of improving the adhesive primer haveheretofore been tried by adding thereto a photopolymerization initiator,which, however, could not produce the intended effect up to the present.As a result, the polymerization of the monomers in the bonding material(including the adhesive primer) applied to the surface of a tooth isinsufficient, and, in a certain period of time after the restoration ofthe tooth with a restorative dental material, a crevice is formedbetween the tooth and the butted material to cause marginal leakage, orthe butted material is peeled off. Such problems with the adhesiveprimer have heretofore been often pointed out. In particular, it is saidthat the problems are remarkable when the bonding material is irradiatedby light for a short period of time.

Improving the polymerization curability of the adhesive primer end thebonding material could be attained in some degree by increasing theamount of the photopolymerization initiator in those compositions.Increasing the amount of the initiator too much in those compositions isproblematic in that the initiator remaining in the cured products of thecompositions will be much released out, since the initiator has nopolymerizable group, and, in addition, the mechanical strength of thecured products is lowered and the cured products are discolored with thelapse of time. In that condition, aesthetic tooth crown repairing isimpossible. For these reasons, adding too much initiator to thecompositions is impracticable.

There is still another problem of secondary caries and odontitis thatmay be caused by the penetration of bacteria into the bonded interfacebetween tooth and the restorative dental material applied thereto, inaddition to the bonding durability failure in the bonding material used.The problem is often pointed out as serious.

For preventing the penetration of bacteria into the bonded interface,antibacterial dental bonding materials have been proposed. For examplesJP-A-1-17107 discloses dental cement that contains an antibacterialagent. JP-A-2-16176 and B-198723 disclose a pre-treating agent fordental use that contains a quaternary alkylammonium salt. In these, theydo not specifically refer to the antibacterial property of thepre-treating agent, but the quatemaryalkylammonium salt used will haveantibacterial ability. However, the antibacterial agent and thequaternary alkylammonium salt have no polymerizable group, and will betherefore released out into the mouth after the dental bondingcomposition comprising any of them has been polymerized and cured on atooth. Prior to their dental application, therefore, the antibacterialagent and the quaternary alkylammonium salt require complete safetyevaluation. Another problem with them is that the antibacterial agentand the quaternary alkylammonium salt do not exhibit the antibacterialability for a long period of time.

JP-A-6-9725 and 7-215814 disclose dental compositions containing anantibacterial polymerizable monomer and an acid group-havingpolymerizable monomer. The antibacterial property as referred to inthese is the non-releasing antibacterial property of the polymerized (orcured) products of the dental compositions. Here, the cured products donot release the antibacterial component from them. These publicationsindicate that the cured products as formed through copolymerization ofthe antibacterial polymerizable monomer and the other monomer exhibitthe antibacterial ability on their surface. Specifically, in the curedpolymer products of the dental compositions proposed, the unpolymerizedantibacterial compound is exposed out on the surface of the curedpolymer, and it may attenuate the bacteria having adhered on the surfaceof the cured products, but could not kill the bacteria existing in thefine structure of the bonded interface of tooth tubules.

One means of solving the problem has been proposed in JP-A 8-157318,which discloses an antibacterial adhesive primer comprising anantibacterial polymerizable monomer, an acid group-containingpolymerizable monomer, an alcoholic hydroxyl group-containingpolymerizable monomer, water and a polymerization catalyst.

The technique proposed is characterized in that an antibacterialpolymerizable monomer is added to the adhesive primer for killingbacteria in and around teeth while, at the same time, attainingdecalcification of teeth, and that the polymerized and cured product ofthe primer composition exhibits a non-releasing antibacterial ability onits surface. Therefore, this is an extremely useful technique. However,the adhesive primer contains a large amount of slightly-volatilecomponents such as the acid group-containing polymerizable monomer andthe alcoholic hydroxyl group-containing polymerizable monomer.Therefore, the probability of contact between bacteria and theantibacterial polymerizable monomer in a resultant product is low, andthe adhesive primer could not satisfactorily express the antibacterialability. In addition, when cured on a tooth the adhesive primer gives alayer of a copolymer of the antibacterial polymerizable monomer andother polymerizable monomers in and around the bonded interface betweenits cured product and the tooth. However, since the proportion of otherpolymerizable monomers to the antibacterial monomer is large, theadhesive primer could not still produce a satisfactory antibacterialeffect.

Greatly increasing the amount of the antibacterial polymerizable monomeror greatly decreasing the amount of the acid group-containingpolymerizable monomer and that of the alcoholic hydroxylgroup-containing polymerizable monomer in the adhesive primer couldimprove the antibacterial ability of the adhesive primer in some degree,which, however, is not practicable as greatly lowering the bonding forceof the adhesive primer to a tooth.

A composition comprising an antibacterial polymerizable monomer and avolatile solvent is known. For example, as in JP-A-9-67546, anantibacterial polymerizable monomer may be added to an adhesivecomposition comprising a monomer capable of bonding to metal and avolatile solvent. However, the adhesive composition disclosed inJP-A-9-67546 is directed to modification of the surface of metal, andnothing is referred to therein that relates to a technique of killingbacteria in and around a tooth. The present inventors tested thecompositions of the examples disclosed in JP-A-9-67546, but thecompositions did not have high bonding strength to a tooth.

JP-A-10-236915 discloses an antibacterial caries-detecting liquid thatcomprises an antibacterial polymerizable monomer, a dye, and waterand/or a water-miscible solvent. Basically, this liquid is applied to atooth before the affected tooth is removed from the tooth with a cuttingtool, thereby killing the cariogenic bacteria that exist in and aroundthe affected tooth while differentiating the affected-tooth from thenon-affected healthy tooth, and the technique disclosed is very useful.However, most of the antibacterial polymerizable monomer in theantibacterial caries-detecting liquid is removed along with the affectedtooth which is removed with a cutting tool. In that condition, a highconcentration of the monomer could not be in and around the toothtreated with the liquid. Therefore, even though the liquid could killthe cariogenic bacteria existing in and around tooth, it is almostcompletely ineffective against the cariogenic bacteria that maypenetrate into the restored area of a tooth, and therefore could notprevent the growth of the cariogenic bacteria penetrated into that areaafter treatment.

Accordingly, there remains a need for compositions and methods whichovercome the problems described above.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide bonding compositionssuitable for dental use.

It us another object of the invention to provide bonding compositionswhich can inhibit the growth of cariogenic bacteria in the bonded areaof a tooth when restored with a restorative dental material, therebypreventing secondary caries and odontitis around that area, and whichcan enhance the bonding strength, especially the bonding durability ofthe restorative dental material, to a tooth.

To accomplish the objects noted above, the present inventors haveassiduously studied the problem of how to prevent the growth ofcariogenic bacteria in the bonded area of tooth as restored with arestorative dental material and of how to entrance the bondingcurability of a restorative dental material and a tooth as restored withthe material, and, as a result, have discovered the following noveltechniques.

Technique for Preventing the Growth of Cariogenic Bacteria

An antibacterial primer comprising a specific antibacterialpolymerizable monomer and a volatile solvent is applied around thesurface of a tooth, and then dried spontaneously or through dental airblowing so as to make a high concentration of the antibacterial,polymerizable monomer on the tooth surface, thereby killing the bacteriahaving adhered on the surface of tooth of the tooth. Thereafter, anadhesive composition that comprises an acid group-containingpolymerizable monomer, a polymerizable monomer and a polymerizationinitiator is applied to the area of the tooth, and is cured along withthe antibacterial monomer previously applied thereto, thereby forming anantibacterial polymer layer having a high concentration at the interfacebetween the tooth and the bonding material. Bacteria that may penetrateinto the bonded interface are killed by the antibacterial polymer layer,and the polymer existing in the bonded interface retains itsantibacterial ability for a long period of time.

Technique of Enhancing Bonding Durability of Bonding Compositions

The adhesive composition described above is composed of twocompositions, one being an adhesive primer that comprises an acidgroup-containing polymerizable monomer, a hydrophilic polymerizablemonomer and water, and the other being a bonding agent that comprises apolymerizable monomer and a polymerization initiator. The adhesivecomposition of this type is a so-called self-etching adhesive component.The photopolymerization initiator in the bonding agent contains both anacylphosphine oxide compound and an α-diketone compound. The adhesiveprimer is first applied to a tooth and is cured along with the bondingagent within a short period of time to form a hard cured layer on thetooth by which the bonding durability of the cured layer to a tooth isenhanced.

Based on the techniques as described above, the present inventors havediscovered that the bonding compositions according to the presentinvention significantly prevent the growth of cariogenic bacteria in thebonded area between tooth and restorative dental material appliedthereto and enhance the bonding strength, especially the bondingdurability between tooth and a restorative dental material appliedthereto, as compared with conventional bonding compositions.

Accordingly, the objects of the invention, and others, may beaccomplished with an antibacterial bonding composition suitable fordental use, comprising:

(A) an antibacterial primer comprising (i) an antibacterialpolymerizable monomer containing an ethylenic unsaturated group and atleast one cationic group selected from the group consisting of ammoniumbases, pyridinium bases and phosphonium bases, and (ii) a volatilesolvent; and

(B) an adhesive composition comprising (i) a first polymerizable monomercontaining an acid group, (ii) a second polymerizable monomer, and (iii)a polymerization initiator.

The objects of the invention may also be accomplished with an adhesivecomposition suitable for dental use, comprising:

(P) an adhesive primer comprising (i) a polymerizable monomer containingan acid group, (ii) a hydrophilic polymerizable monomer, and (iii)water; and

(Q) a bonding agent comprising (i) a polymerizable monomer, (ii) anacylphosphine oxide compound, and (iii) an α-diketone compound.

The objects of the invention may also be accomplished with anantibacterial bonding composition suitable for dental use, comprising:

(A) an antibacterial primer comprising (i) an antibacterialpolymerizable monomer containing an ethylenic unsaturated group and atleast one cationic group selected from the group consisting of ammoniumbases, pyridinium bases and phosphonium bases, and (ii) a volatilesolvent;

(P) an adhesive primer comprising (i) a polymerizable monomer containingan acid group, (ii) a hydrophilic polymerizable monomer, (iii) water,and (iv) a polymerization initiator; and

(Q) a bonding agent comprising a (i) polymerizable monomer, (ii) apolymerizable monomer containing an acid group, (iii) an acylphosphineoxide compound, and (iv) an α-diketone compound,

where the ratio of the acylphosphine oxide compound to the α-diketonecompound is 1:0.01 to 1:0.5.

The objects of the invention may also be accomplished with a compositionsuitable for dental use, comprising:

(a) an antibacterial polymerizable monomer containing an ethylenicunsaturated group and at least one cationic group selected from thegroup consisting of ammonium bases, pyridinium bases and phosphoniumbases;

(b) an a polymerizable monomer containing an acid group;

(c) an additional polymerizable monomer; and

(d) a polymerization initiator.

The objects of the invention may also be accomplished with a method ofproviding an antibacterial coating on a tooth, comprising curing thecomposition described above on the tooth.

The objects of the invention may also be accomplished with a method ofapplying an antibacterial coating to a tooth, comprising:

applying to a tooth a first composition comprising (i) an antibacterialpolymerizable monomer containing an ethylenic unsaturated group and atleast one cationic group selected from the group consisting of ammoniumbases, pyridinium bases and phosphonium bases, and (ii) a volatilesolvent;

removing at least a portion of the volatile solvent;

applying to a tooth a second composition comprising (i) a firstpolymerizable monomer containing an acid group, (ii) a secondpolymerizable monomer, and (iii) a polymerization initiator; and then

curing the applied compositions.

A more complete appreciation of the invention and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description.

DETAILED DESCRIPTION OF THE INVENTION

The term “adhesive composition” as used herein refers to an adhesive forbonding a restorative dental material to a tooth, and this includes anadhesive primer that is applied to a tooth or to a restorative dentalmaterial prior to bonding the tooth and the material so as to enhancethe bonding strength between the two. Specifically, the adhesivecompositions in the invention encompasses any combination of two or morecompositions that may be wrapped or packaged separately, for example, acombination of an adhesive primer and a bonding agent, or a combinationof an adhesive primer and a resin cement.

The antibacterial polymerizable monomer for use in the invention has anethylenic unsaturated group and at least one cationic group selectedfrom the group consisting of ammonium bases, pyridinium bases andphosphonium bases. For example, generally used are antibacterialpolymerizable monomers of the following general formulae (I) to (IV):

wherein

R¹=H or CH₃,

R²=alkylene group having 2-25 carbon atoms,

X=O, S, NH,

—CH₂O— or —OCH₂—,

a=0 or 1,

b=0 or 1,

R³=H or —(V)_(c)—R⁷—W,

R⁴, R⁵, R⁶=(V)_(c)—R⁷—W,

V=O, S, NH,

—CH₂O— or —OCH₂—,

R⁷=alkylene group having 1-25 carbon atoms,

W=H, CH₃, OH or

c=0 or 1,

Z=anion.

wherein

R⁸=H or CH₃,

R⁹=alkylene group having 2-25 carbon atoms,

X=O, S, NH,

—CH₂O— or —OCH₂—,

d=0 or 1,

e=0 or 1,

R¹⁰=H or —(V)_(f)—R¹³—W,

R¹¹, R¹²=(V)_(f)—R¹³—W,

V=O, S, NH

—CH₂O— or —OCH₂—,

R¹³=alkylene group having 1-25 carbon atoms,

W=H, CH₃, OH or

f=0 or 1,

Z=anion.

wherein

R¹⁴=H or CH₃,

R¹⁵=alkylene group having 2-25 carbon atoms,

X=O, S, NH,

—CH₂O— or —OCH₂—,

g=0 or 1,

h=0 or 1,

R¹⁶, R¹⁷, R¹⁸=(V)₁—R¹⁹—W,

V=O, S, NH,

—CH₂O— or —OCH₂—,

R¹⁹=alkylene group having 1-25 carbon atoms,

W=H, CH₃, OH or

i=0 or 1,

Z=anion.

wherein

R²⁰=H or CH₃,

R²¹, R²²=alkylene group having 1-25 carbon atoms,

j=0 or 1,

k=0 or 1,

A=O, S, NH,

—CH₂O— or —OCH₂—,

B¹, B²,=—CO—, —COO—, —OCO—, —O—, —S—, —NHCOO— or —OCONH—,

R²³=—(V)_(p)—R²⁴W′,

V=O, S, NH,

—CH₂O— or —OCH₂—,

R²⁴=alkylene group having 1-25 carbon atoms,

W¹=H, CH₃, OH,

p=0 or 1,

Z=anion.

Specific examples of the compounds of formula (I) include the following:

Specific examples of the compounds of formula (II) include thefollowing:

Specific examples of the compounds of formula (III) include thefollowing:

Specific examples of the compounds of formula (IV) include thefollowing:

Among these monomers, preferred are the antibacterial polymerizablemonomers having an alkylene group with 10 or more carbon atoms, whichexhibit good antibacterial properties. Such monomers include, forexample, methacryloyloxydodecylpyridinium salts,methacryloyloxyhexadecylpyridinium salts,methacryloyloxydecyltriethylammonium salts,4-hexadecylmethacryloyloxyethylpyridinium salts,methacryloylaxyethylhexadecylbipyridinium salts,methacryloyloxydodecyltrimethylphosphonium salts,methacryloyloxyoctadecyltriethylphosphonium salts,4-methacryloyloxyethyldodecylpyrldinium salts,di(4-vinylbenzyl)hexadecylmethylammonium salts,di(methacryloyloxyethyl)dodecylmethylammonium salts,methacryloyloxyethyl(4-N-hexadecylpyridinylmethyl) succinate halides,etc.

In the antibacterial polymerizable monomers, the anions which areformally paired with the ammonium cation, the pyridinium cation and thephosphonium cation are not particularly limited. They include, forexample, halides such as F⁻, Cl⁻, Br⁻, I⁻; anions derived from inorganicacids such as PO₄ ³⁻, HPO₃ ²⁻, H₂PO₄ ⁻, Na₂PO₃ ²⁻, Na₂PO₃ ⁻, SO₄ ²⁻,HSO₄ ⁻, KSO₄ ⁻, NO₃ ⁻ etc.; anions derived from organic acids such asmethanesulfonic acid, acetic acid, propionic acid, benzoic acid, phenol,p-toluenesulfonic acid, maleic acid, oxalic acid, citric acid, etc.; andalso anions derived from polymerizable acidic compounds that will bementioned hereinunder. They further include anions derived frompolymerizable acids such as AlF₆ ³⁻, AsFe⁻, BF₄ ⁻, BiCl₄ ²⁻, BiCl₃ ²⁻,SbCl₆ ⁻, SbF₆ ⁻, PF₆ ⁻, GaCl₄ ⁻, InF₄ ⁻, TiF₆ ²⁻, ZrF₆ ⁻, FeCl₄ ⁻, SnCl₆⁻, etc. Halides are the preferred anions. These anions are paired withthe cations, either singly or as combined.

One or more antibacterial polymerizable monomers may be used hereineither singly or as combined, i.e., as a mixture. The amount of theantibacterial polymerizable monomer in the antibacterial primer maygenerally fall between 0.000001% by weight and 50% by weight, preferablybetween 0.001% by weight and 30% by weight, more preferably between0.01% by weight and 10% by weight, based on the total weight of theprimer. These ranges include all specific values and subrangestherebetween, such as 0.0001, 0.01, 0.1, 0.5, 1, 2, 5, 15, 20 and 25% byweight, based on the total weight of the primer. The ranges describedabove, and those described below, include the endpoints unless notedotherwise.

In the present invention, the volatile solvent in the antibacterialprimer has the ability to dissolve the antibacterial polymerizablemonomer. The solvent includes, for example, volatile organic solventshaving a boiling point at ordinary pressure of not higher than 250° C.,water, and mixtures thereof. Examples of volatile organic solventsinclude alcohols such as methanol, ethanol, 2-ethylbutanol isopropanol;ketones such as acetone, methylethyl ketone, 2-butanone, 3-pentanone;ethers such as diethyl tetrahydrofuran; as well as ethyl acetate,toluene, xylene, p-cymene, hexane, octane, pentane, methylene chloride,1,2-dichloroethane, methyl methacrylate.

Of those, preferred are volatile organic solvents having a boiling pointat ordinary pressure of not higher than 100° C., such as ethanol,acetone. One or more of those solvents may be used either singly or incombination, i.e., solvent mixtures may be used.

The amount of the solvent in the antibacterial primer may generally fallbetween 50% by weight and 99.999999% by weight, preferably between 70%by weight and 99.9999% by weight, more preferably between 90% by weightand 99.99% by weight, based on the total weight of the primer. Theseranges include all specific values and subranges therebetween, such as60, 75, 80, 85, 90, 95, 99, and 99.9% by weight, based on the totalweight of the primer.

In some embodiments, it is often desirable to add polymerizationinitiator to the antibacterial primer which comprises an antibacterialpolymerizable monomer and a volatile solvent such as those noted above,for the purpose of more firmly curing the antibacterial polymerizablemonomer. The polymerization initiator is not specifically limited, andmay be any inhibitor well-known to those skilled in the art.

Photopolymerization initiators may be used, including, for example,α-diketone/reducing agent, ketal/reducing agent, thioxanthone/reducingagent, etc. Examples of the α-diketone include camphorquinone, benzil,2,3-pentanedione, etc. Examples of the ketal include benzyldimethylketal, benzyldiethyl ketal, etc. Examples of the thioxanthone include2-chlorothioxanthone, 2,4-diethylthioxanthone, etc. Examples of thereducing agent include tertiary amines such as 2-(dimethylamino)ethylmethacrylate, N,N-bis[(meth)acryloyloxyethyl]-N-methylamine, ethyl4-dimethylaminobenzoate, butyl 4-dimethylaminobenzoate, butoxyethyl4-dimethylaminobenzoate, N-methyldiethanolamine,4-dimethylaminobenzophenone, dimethylaminophenanthol, etc., aldehydessuch as dimethylaminobenzaldehyde, terephthalaldehyde, etc.; thiolgroup-having compounds such as 2-mercaptobenzoxazole, decanethiol,3-mercaptopropyltrimethoxysilane, thiobenzoic acids etc. Forphotopolymerization through UV exposure, preferable examples includebenzoin alkyl ethers, benzyldimethyl ketal, etc.

Also preferably used are acylphosphine oxide compounds, which include,for example, 2,4,6-trimethylbenzoyldiphenylphosphine oxide,2,6-dimethoxybenzoyldiphenylphosphine oxide,2,6-dichlorobenzoyldiphenylphosphine oxide,2,3,5,6-tetramethylbenzoyldiphenylphosphine oxide,benzoyldi-(2,6-dimethylphenyl) phosphonate,2,4,6-trimethylbenzoylethoxyphenylphosphine oxide, as well aswater-soluble acylphosphine oxides such as those disclosed inJP-B-3-57916. These acylphosphine oxide compounds may be used eithersingly or as combined with a reducing agent of, for example, variousamines, aldehydes, mercaptans, salts of sulfinic acids, etc.

One or more of these photopolymerization initiators and reducing agentsmay be used herein, i.e., mixtures may be used. The amount of thephotopolymerization initiator and the reducing agent in theantibacterial primer may generally fall between 0.01% by weight and 20%by weight, preferably between 0.01% by weight and 10% by weight, morepreferably between 0.1% by weight and 5% by weights based on the totalweight of the antibacterial primer. These ranges include all specificvalues and subranges therebetween, such as 0.02, 0.05, 1, 2, 5, 10 and15% by weight, based on the total weight of the antibacterial primer.

Chemical polymerization initiators are also employable herein, which arepreferably redox polymerization initiators. Where such a redoxpolymerization initiator is used for the antibacterial primer whichconstitutes the bonding composition of the invention, the antibacterialprimer should be divided into at least two parts which are separatelywrapped or packaged and which separately contain either one of theoxidizing agent and the reducing agent for the initiator. However, inpractical use of the antibacterial bonding composition of the invention,the antibacterial primer shall be all the time combined with the otherconstituent component of the adhesive component. Therefore, in thecomposition, the oxidizing agent and the reducing agent for theinitiator may be separately incorporated into the antibacterial primerand the adhesive component.

The oxidizing agent may be an organic peroxide, including, for example,diacyl peroxides, peroxy esters, dialkyl peroxides, peroxy ketals,ketone peroxides, hydroperoxides, etc. Specific examples of the diacylperoxides include benzoyl peroxide, 2,4-dichlorobenzoyl peroxide,m-toluoyl peroxide, etc.

The peroxy esters include, for example, t-butylperoxy benzoate,bis-t-butylperoxy isophthalate,2,5-dimethy-2,5-bis(benzoylperoxy)hexane, t-butylperoxy2-ethylhexanoate, t-butylperoxyisopropyl carbonate, etc.

The dialkyl peroxides include, for example, dicumyl peroxide, di-t-butylperoxide, lauroyl peroxide, etc.

The peroxy ketals include, for example,1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane,2,2-bis(t-butylperoxy)butane, 1,1-bis(t-butylperoxy)cyclohexane, etc.

The ketone peroxides include, for example, methyl ethyl ketone peroxide,cyclohexanone peroxide, methyl acetacetate peroxide, etc.

The hydroperoxides include, for example, t-butylhydroperoxide,cumenehydroperoxide, p-diisopropylbenzeneperoxide, etc. One or morethese oxidizing agents may be used either singly or as combined.

As the reducing agent, preferred are aromatic tertiary amine, aliphatictertiary amines, as well as sulfinic acids, and salts thereof.

The aromatic tertiary amines include, for example, N,N-dimethylaniline,N,N-dimethyl-p-toluidine, N,N-dimethyl-m-toluidine,N,N-diethyl-p-toluidine, N,N-dimethyl-3,5-dimethylaniline,N,N-dimethyl-3,4-methylaniline, N,N-dimethyl-4-ethylaniline,N,N-dimethyl-4-t-propylaniline, N,N-dimethyl-4-t-butylaniline,N,N-dimethyl-3,5-di-t-butylaniline, N,N-di(2-hydroxyethyl)-p-toluidine,N,N-di(2 hydroxyethyl)-3,5-dimethylaniline,N,N-di(2-hydroxyethyl)-3,4-diethylaniline,N,N-di(2-hydroxyethyl)-4-ethylaniline,N,N-di(2-hydroxyethyl)-4-i-propylaniline,N,N-di(2-hydroxyethyl)-4-t-butylaniline,N,N-di(2-hydroxyethyl)3,5-di-i-propylaniline,N,N-bis(2-hydroxyethyl)-3,5-di-t-butylaniline, ethyl4-dimethylamonobenzoate, n-butoxyethyl 4-dimethylaminobenzoate,(2-methacryloyloxy)ethyl, 4-dimethylaminobenzoate, etc.

The aliphatic tertiary amines include, for example, trimethylamine,triethylamine, N-methyldiethanolamine, N-ethyldiethanolamine,N-n-butyldiethanolamine, N-lauryldiethanolamine, triethanolamine,(2-dimethylamino)ethyl methacrylate, N-methyldiethanolaminedimethacrylate, N-ethyldiethanolamine dimethacrylate, triethanolaminemonomethacrylate, triethanolamine dimethacrylate, triethanolaminetrimethacrylate, etc.

The sulfinic acids end their salts include, for example, benzenesulfinicacid, sodium benzenesulfinate, potassium benzenesulfinate, calciumbenzenesulfinate, lithium benzenesulfinate, toluenesulfinic acid, sodiumtoluenesulfinate, potassium toluenesulfinate, calcium toluenesulfinate,lithium toluenesulfinate, 2,4,6-trimethylbenzenesulfinic acid, sodium2,4,6-trimethylbenzenesulfinate, potassium2,4,6-trimethylbenzenesulfinate, calcium2,4,6-trimethylbenzenesulfinate, lithium2,4,6-trimethylbenzenesulfinate, 2,4,6-triethylbenzenesulfinic acid,sodium 2,4,6-riethylbenzenesulfinate, potassium2,4,6-triethylbenzenesulfinate, calcium 2,4,6-triethylbenzenesulfinate,2,4,6-i-propylbenzenesulfinic acid, sodium2,4,6-i-propylbenzenesulfinate, potassium 2,4,6-propylbenzenesulfinate,calcium 2,4,6-i-propylbenzenesulfinate, etc.

One or more of these reducing agents may be used either singly or incombination.

The amount of the oxidizing agent and the reducing agent in the bondingcomposition of the invention may generally fall between 0.0001% byweight and 20% by weight, preferably between 0.01% by weight and 10% byweight, more preferably between 0.1% by weight and 5% by weight, basedon the total weight of the antibacterial primer that constitutes thecompositions. These ranges include all specific values and subrangestherebetween, including 0.001, 0.2, 0.5, 1, 2, 10 and 15% by weight,based on the total weight of the antibacterial primer.

The antibacterial primer of the invention may optionally containinorganic acids such as phosphoric acid, nitric acid, etc., organicacids such as maleic acid, citric acid etc., as well as polymerizationinhibitors, antioxidants, UV absorbents, pigments, dyes and otheradditives, in addition to the components described above. Any additionalpolymerizable monomer may also be incorporated into the antibacterialprimer, so long as it does not significantly interfere with theantibacterial capabilities of the primer. The amount of the additionalpolymerizable monomer, if any, in the antibacterial primer is generallyat most 30% by weight, preferably at most 10% by weight, based on thetotal weight of the antibacterial primer. A fluorine compound havinganticarious capabilities, such as sodium fluoride, may also beincorporated in the primer.

The antibacterial primer of the invention may also contain a filler. Thefiller may be any of organic, inorganic or even composite fillers. Theinorganic fillers include, for example, silica, silica-based mineralssuch as kaolin, clay, mica, eta.; and silica-based ceramics and glassadditionally containing any of Al₂O₃, B₂O₃, TiO₂, ZrO₂, BaO, La₂O₃,SrO₂, CaO, P₂O₅, etc. Especially preferred are lanthanum glass, bariumglass, strontium glass, soda glass, lithium borosilicate glass, zincglass, fluoroaluminium borosilicate glass, borosilicate glass, bioglass,etc. Also preferred are crystalline quartz, hydroxyapatite, alumina,titanium oxide, yttrium oxide, zirconia, calcium phosphate, bariumsulfate, aluminium hydroxide, etc.

The organic fillers may be an organic resin, including, for example,polymethyl methacrylate, polymers of polyfunctional methacrylates,polyamides, polystyrenes, polyvinyl chloride, chloroprene rubber,nitrile rubber, styrene-butadiene rubber, etc.

Also useful herein are inorganic/organic composite fillers, which may beprepared by dispersing an inorganic filler in an organic resin, or bycoating an inorganic filler with an organic resin.

If desired, the fillers may be previously subjected to surface treatmentwith any known surface-treating agent such as a silane coupling agent orthe like. The surface-treated fillers are effective for controlling thefluidity of the antibacterial primer and for enhancing thedispersibility thereof. The surface-treating agent includes, forexample, vinyltrimethoxysilane, vinyltriethoxysilane,vinyltrichlorosilane, vinyltri(β-methoxyethoxy)silane,γ-methacryloyloxypropyltrimethoxysilane,γ-glycidoxypropyl-trimethoxysilane, γ-mercaptopropyltrimethoxysilane,and aminopropyltriethoxysilane.

One or more those fillers may be used either singly or as combined. Theamount of the filler, if any, in the antibacterial primer is generallyat most 30% by weight, preferably at most 10% by weight, based on thetotal weight of the primer. As the filler, more preferred is colloidalsilica having a mean particle size of at most 0.1 μm.

The acid group-containing polymerizable monomer in the adhesivecomposition of the invention is a polymerizable monomer which containsat least one acid group. For example, the acid group may be a phosphoricacid residue, a pyrophosphorio acid residue, a thiophosphoric acidresidue, a carboxylio acid residue, a sulfonic acid residue or the like,and has a polymerizable unsaturated group of, for example, an acryloylgroup, a methacryloyl group, a vinyl group, a styrene group or the like.Specific examples of the monomer are described below. The terminology“(meth)acryl” as used herein includes both “methacryl” and “acryl”.

The polymerizable monomers having a phosphoric acid residue include, forexample, 2-(meth)acryloyloxyethyl dihydrogenphosphate,4-(meth)acryloyloxybutyl dithydrogenphosphate, 6-(meth)acryloyloxyhexyldihydrogenphosphate, 8-(meth)acryloyloxyoctyl 9-(meth)acryloyloxynonyldihydrogenphosphate, 10-(meth)acryloyloxydecyl dihydrogenphosphate,11-(meth)acryloyloxyundecyl dihydrogenphosphate,20-(meth)acryloyloxyeicosyl dihydrogenphosphate,1,3-di(meth)acryloyloxypropyl-2-dihydrogenphosphate,dihydrogenghosphate, 2-(meth)acryloyloxyethylphenyl phosphate,2-(meth)acryloyloxyethyl-2′-bromoethyl phosphate,(meth)acryloyloxyethylphenyl phosohonate, and their acid chlorides.

The polymerizable monomers having a pyrophosphine acid residue include,for example, di(2-(meth)acryloyloxyethyl) pyrophosphate,di(2-(meth)acryloyloxybutyl) pyrophosphate, di(2-(meth)acryloyloxybexyl)pyrophosphate, di(2-(meth)acryloyloxydecyl) pyrophosphates, and theiracid chlorides.

The polymerizable monomers having a thiophosphoric acid residue include,for example, 2-(meth)acryloyloxyethyl dihydrogendithiophosphate,10-(meth)acryloyloxydecyl dihydrogendithiophosphate, and their acidchlorides.

The polymerizable monomers having a carboxylic acid residue include, forexample, maleic acid, maleic anhydride,4-(meth)acryloyloxyethoxycarbonylphthalic acid,4-(meth)acryloyloxyethoxycarbonylphthalic anhydride,5-(meth)acryloylaminopentylcarboxylic acid,11-(meth)aryloyloxy-1,1-undecanedicarboxylic acid, and their acidchlorides.

The polymerizable monomers having a sulfonic acid residue may becompounds having a sulfonic acid group, such as, for example,2-(meth)acrylamido-2-methylpropanesulfonic acid, styrenesulfonic acid,2-sulfoethyl(meth)acrylate, etc.

One or more those acid group-containing polymerizable monomers may beused herein either singly or in combination, i.e., mixtures of differentacid group-containing monomers may be used.

The amount of the acid group-containing polymerizable monomer in theadhesive component may generally fall between 0.1% by weight and 80% byweight, preferably between 1% by weight and 60% by weight, based on thetotal weight of the adhesive composition. These ranges include allspecific values and subranges therebetween, such as 0.02, 0.05, 2, 5,10, 25, 50 and 75% by weight, based on the total weight of the adhesivecomposition.

Examples of the other polymerizable monomer which is also in theadhesive composition include, esters of α-cyanoacrylic acid,(meth)acrylic acid, α-halogenoacrylic acids, crotonic acid, cinnamicacid, sorbic acid, maleic acid, itaconic acid and the like; as well as(meth)acrylamide, (meth)acrylamide derivatives, vinyl esters, vinylethers, mono-N-vinyl derivatives, styrene derivatives, etc. Of those,(meth)acrylates are preferred. Examples of the polymerizable monomersare described below.

The terminology “monofunctional monomer” as referred to herein means toindicate a monomer haying one olefinic double bond.

(i) Monofunctional Monomers

These include, for example, methyl (methacrylate, iso-butyl(meth)acrylate, benzyl (meth)acrylate, lauryl (meth)acrylate,2-(N,N-dimethylamino)ethyl (meth)acrylate, 2,3-dibromopropyl(meth)acrylate, 3-methacryloyloxypropyltrimethoxysilane, 2-hydroxyethyl(meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 10-hydroxydecyl(meth)acrylate, propylene glycol mono(meth)acrylate, glycerinmono(meth)acrylate, erythritol mono(meth)acrylate,N-methylol(meth)acrylamide, N-hydroxyethyl(meth)acrylamide,N,N-(dibydroxyethyl)(meth)acrylamide, (meth)acryloylaxydodecylpyridiniumbromide, (meth)acryloyloxydodecylpyridinium chloride,(meth)acryloyloxyhexdodecylpyridinium bromide,(meth)acryloyloxyhexdodecylpyridinium chloride.

(ii) Difunctional Monomers

These include, for example, ethylene glycol di(meth)acrylate,triethylene glycol di(meth)acrylate, polyethylene glycoldi(meth)acrylate, propylene glycol di(meth)acrylate, neopentyl glycoldi(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,10-decanedioldi(meth)acrylate, bisphenol A diglycidyl(meth)acrylate,2,2-bis[4-(meth)acryloyloyethoxyphenyl]propane,2,2-bis[4-(meth)acryloyloxypolyethoxyphenyl]propane, 2,2-bis[4-[3-(meth)acryloyloxy-2-hydroxypropoxy]phenyl]propane,1,2-bis[3-(meth)acryloyloxy-2-hydroxypropoxy]ethane, pentaerythritoldi(meth)acrylate, 1,2-bis(3-methacryloyloxy-2-hydroxypropoxy)ethane,[2,2,4-trimethylhexamethylenebis(2-carbamoyloxyethyl)] dimethacrylate.

(iii) Trifunctional or Higher Polyfunctional Monomers

They include, for example, trimethylolpropane tri(meth)acrylate,trimethylolethane tri(meth)acrylate, tetramethylolmethanetri(meth)acrylate, pentaerythritol tetra(meth)acrylate, N,N′-(2,2,4,trimethylhexamethylene)bis[2-(aminocarboxy)propane-1,3-diol]tetramethacrylate,1,7-diacryloyloxy-2,2,6,6-tetracryloyloxymethyl-4-hydroxyheptane.

One or more of these polymerizable monomers may be used either singly orin combination.

The amount of the polymerizable monomer in the adhesive composition maygenerally fall between 5 and 95% by weight, preferably between 30 and90% by weight, more preferably between 40 and 80% by weight, based onthe total weight of the adhesive component. These ranges include allspecific values and subranges therebetween, such as 10, 15, 20, 25, 50,75 and 90% by weight, based on the total weight of the adhesivecomponent.

The polymerization initiator in the adhesive composition is importantfor curing both the adhesive component and the antibacterial primer, andis not particularly limited. Any of the well-known polymerizationinitiators known may be used in the present invention. Thepolymerization initiator may be any of the well-knownphotopolymerization initiators and/or chemical polymerizationinitiators.

For the photopolymerization initiators usable in the adhesive component,examples include those described above for the antibacterial primer. Thesame initiator in the antibacterial primer mentioned hereinabove mayalso be in the adhesive component. Especially preferred for the adhesivecomponent is a combination of α-diketone/acylphosphine oxide/reducingagent.

One or more photopolymerization initiators and also reducing agents maybe used either singly or as combined. The amount of thephotopolymerization initiator and the reducing agent in the adhesivecomposition may generally fall between 0.01 and 20% by weight,preferably between 0.1 and 5% by weight, based on the total weight ofthe adhesive composition. These ranges include all specific values andsubranges therebetween, such as 0.02, 0.05, 0.2, 0.5, 1, 2, 8, 10 and15% by weight, based on the total weight of the adhesive composition.

When the adhesive composition of the invention will be exposed to theambient light, the composition should be protected from being thickened,gelled or cured owing to the ambient light within a short period oftime. For this purpose, it is desirable that the total amount of theacylphosphine oxide compound and the α-diketone compound is limited tofall between 1% by weight and 6% by weight. More preferably, the ratioof the acylphosphine oxide compound to the α-diketone compound in theadhesive composition is so defined that the latter is from 0.01 parts byweight to 0.5 parts by weight based on one part by weight of the former.In the ratio defined above, the adhesive composition is stable even inthe ambient light and its photocurability is high.

Chemical polymerization initiators are also employable herein, which arepreferably redox polymerization initiators. Where such a redoxpolymerization initiator is used for the adhesive composition, theadhesive composition must be divided into at least two parts which areseparately wrapped or packaged and which separately contain either oneof the oxidizing agent and the reducing agent for the initiator.However, where the adhesive composition is combined with theantibacterial primer described above to constitute the antibacterialbonding compositions of the invention, any one of the oxidizing agentand the reducing agent for the initiator may be incorporated in eitherthe antibacterial primer or the adhesive composition. In that case, theadhesive composition may be in the form of a single package.

For the oxidizing agents and the reducing agents usable in the adhesivecomposition, examples include those described above for theantibacterial primer. The same initiator in the antibacterial primer mayalso be in the adhesive composition.

One or more oxidizing agents and reducing agents may be used eithersingly or as combined. The amount of the oxidizing agent and thereducing agent to be in the adhesive component may generally fallbetween 0.01 and 20% by weight, preferably between 0.1 and 10% byweight, based on the total weight of the adhesive composition. Theseranges include all specific values and subranges therebetween, such as0.02, 0.05, 0.2, 0.5, 1, 2, 5 and 15% by weight, based on the totalweight of the adhesive composition.

The adhesive composition in the invention optionally contain a filler,which is for improving the handlability, the coatability and themechanical strength of the composition. For examples of the filler,referred to are those of inorganic fillers, organic fillers,inorganic/organic composite fillers mentioned hereinabove for theantibacterial primer. The same filler as in the antibacterial primermentioned hereinabove could also be in the adhesive composition.

One or more such fillers may be used either singly or as combined. Theamount of the filler, if any, in the adhesive composition is generallyat most 70% by weight, preferably at most 50% by weight, based on thetotal weight of the adhesive composition. Where the adhesive compositioncontains an organic solvent or water, the amount of the filler thereinis preferably at most 30% by weight. As the filler, especially preferredis colloidal silica having a mean particle size of at most 0.1 μm.

The adhesive composition in the invention may optionally containpolymerization inhibitors, antioxidants, UV absorbents, pigments dyesand other additives in addition to the ingredients noted above. Afluorine compound having anticarious capabilities, such as sodiumfluoride, may be incorporated in the adhesive composition.

Preferably, the adhesive composition of the present invention is dividedinto plural parts, for example, as a combination of an adhesive primerand a bonding agent, or a combination of an adhesive primer and a resincement. The adhesive composition that is in the form of suchcombinations is preferred, because its bonding strength to tooth isgreatly increased. More preferably, the divided parts of the adhesivecomposition selectively contain specific ingredients, as mentionedbelow.

(A) Adhesive Primer

Preferably, the adhesive primer comprises an acid group containingpolymerizable monomer such as those described above (in an amount offrom 5% by weight to 50% by weight), a hydrophilic polymerizable monomerhaving a solubility in water at 25° C. of at least 5% (in an amount offrom 20% by weight to 95% by weight), and water (in an amount of from 5%by weight to 70% by weight). Comprising these components, the adhesiveprimer exhibits improved penetrability into teeth and also improvedadhesiveness to teeth.

More preferably, the adhesive primer also contains a polymerizationinitiator (in an amount of from 0.1 to 5% by weight).

For specific examples of the constituent ingredients in the adhesiveprimer, examples include those described above. In particular, as thehydrophilic polymerizable monomer, preferred are 2-hydroxyethylmethacrylate, 3-hydroxypropoylmethacrylate, polyethylene glycoldimethacrylate in which the number of oxyethylene groups is at least 9).

(B) Bonding Agent

The bonding agent comprises a polymerizable monomer and a polymerizationinitiator, to further enhance the curing of the antibacterial primer andalso the adhesive primer noted above (these primers are applied to atooth prior to the bonding agent), thereby increasing the bondingstrength of the adhesive composition of the invention to a tooth. Morepreferably, the bonding agent contains an acid group-containingpolymerizable monomer such as that mentioned above (in an amount of from1% by weight to 30% by weight) and/or a filler (in an amount of from 1%by weight to 30% by weight). The polymerization initiator in the bondingagent is preferably a photopolymerization initiator.

In the adhesive composition of the invention, in which the adhesivecomposition is divided into two parts of an adhesive primer and abonding agent, the photopolymerization initiator in the bonding agent ispreferably a combination of an acylphosphine oxide compound and anα-diketone compound.

In the preferred embodiment, the adhesive primer and the bonding agentcan be firmly cured within a short period of time to give a curedproduct having increased bonding strength, especially increased bondingdurability.

The acylphosphine oxide compounds include, for example,2,4,6-trimethylbenzoyldiphenylphosphine oxide,2,6-diethylbenzoyldiphenylphosphine oxide,2,6-dimethoxybenzoyldiphenylphosphine oxide,2,6-dichlorobenzoyldiphenylphosphine oxide,2,3,5,6-tetramethylbenzoyldiphenylphosphine oxide,benzoyldi-(2,6-dimethylphenyl) phospbonate,2,4,6-trimethylbenzoylethoxyphenylphosphine oxide, as well aswater-soluble acylphosphine oxides such as those disclosed inJP-B-3-57916.

The α-diketone compounds include, for example, camphorquinone, benzil,and 2,3-pentanedione.

The amount of the acylphosphine oxide compound in the bonding agent maygenerally fall between 0.5% by weight and 10% by weight, preferablybetween 1% by weight and 7% by weight, more preferably between 2% byweight and 5% by weight, based on the total weight of the bonding agent.The amount of the α-diketone compound to be in the bonding agent maygenerally fall between 0.01% by weight and 5% by weight, preferablybetween 0.05% by weight and 3% by weight, more preferably between 0.1%by weight and 1.5% by weight, based on the total weight of the bondingagent.

In general, the acylphosphine oxide compounds and the α-diketonecompounds are combined with a reducing agent of, for example, amines,aldehydes, mercaptans or salts of sulfinic acids, as their ability topromote photopolymerization reaction is enhanced. For specific orpreferred examples of the reducing agent, referred to are thosementioned hereinabove. The amount of the reducing agent to be in thebonding agent may generally fall between 0.5% by weight and 10% byweight, preferably between 0.1% by weight and 5% by weight, based on thetotal weight of the bonding agent.

When the bonding agent of the invention will be exposed to the ambientlight, the bonding agent is preferably protected from being thickened,gelled or cured owing to the ambient light within a short period oftime. For this purpose, it is desirable that the total amount of theacylphosphine oxide compound and the α-diketone compound in the bondingagent is limited to fall between 1% by weight and 6% by weight. Morepreferably, the ratio of the acylphosphine oxide compound to theα-diketone compound in the bonding agent is so defined that the latteris from 0.01 parts by weight to 0.5 parts by weight based on one part byweight of the former. In the defined ratio, the bonding agent is stableeven in the ambient light and its photocurability is high.

If desired, the bonding agent may further contain any otherphotopolymerization initiators and/or chemical polymerizationinitiators, in addition to the acylphosphine oxide compound and theα-diketone compound. For examples of the chemical thephotopolymerization initiators and polymerization initiators, referredto are those mentioned hereinabove.

(C) Resin Cement

The resin cement comprises a polymerizable monomer, a polymerizationinitiator and a filler, and this is for further enhancing the curing ofthe antibacterial primer and also the adhesive primer thereby toincrease the bonding strength of the adhesive composition of theinvention to a tooth and also to increase the abrasion resistance of theresin cement itself. More preferably, the resin cement contains an acidgroup-containing polymerizable monomer such as that mentioned above (inan amount of from 1% by weight to 20% by weight), as the monomer iseffective for much more enhancing the bonding strength of thecomposition of the invention. The amount of the filler to be in theresin cement is preferably from 40%, by weight to 80% by weight. As thefiller, preferred is an X-ray opaque material, such as barium glass.

The adhesive composition of the invention is used in such a manner thatthe antibacterial primer in the compositions is first applied to thesurface of a tooth, then the adhesive composition is applied on it, andthe two are cured thereon. Specific examples of using the adhesivecomposition are described below, which, however, are not limitative.

(1) Direct Restoration and Repairing with Composite Resin

The antibacterial primer of the invention is applied to the cavityformed in a tooth. Then, this is left as such or forcedly dried with adental air syringe to remove the volatile solvent. Next, the adhesivecomposition of the intention is applied on this, and left as such for awhile, or it desired, the coated area is blown with a dental airsyringe. In that condition, the ingredients in the coated area arecured. Where the adhesive composition is composed of two divided partsof an adhesive primer and a bonding agent, the adhesive primer is firstapplied to the intended area, then left as such for a predeterminedperiod of time, and thereafter subjected to air blowing. Next, thebonding agent is applied to that area, and the ingredients are cured.The curing may be effected in any desired manner of photopolymerization,a chemical polymerization or dual curing of photopolymerization andchemical polymerization (hereinafter photo/chemical polymerization).Preferred is photopolymerization for which is used an irradiator, ordual curing polymerization, as being easy to perform.

After the adhesive composition has been cured, composite resin orcomposition for dental restoration is added to the cured area and thencured. By this treatment, the restoration of the tooth is completed.

(2) Indirect Restoration and Repairing with Prosthetic Material

The antibacterial primer of the invention, is first applied to thecavity formed in a tooth. Then, this is left as such or forcedly driedwith a dental air syringe to remove the volatile solvent.

Next, the adhesive composition of the invention is applied to aprosthetic material such as a metal alloy, a ceramic, a cured compositeresin or the like, which is then pressed against the surface of thetooth having been previously the treated with the antibacterial primer,and then cured. Through the treatment, the restoration of the tooth iscompleted. In this case, the adhesive composition may be applied to theantibacterial primer-coated surface of the tooth.

Where the adhesive composition is composed of two divided parts of anadhesive primer and a resin cement, the adhesive primer is first appliedto the surface of the tooth having been previously treated with theantibacterial primer, then left as such for a predetermined period oftime, and thereafter subjected to air blowing. Next the prostheticmaterial is applied to the treated surface of the sooth along with theresin cement, and cured and bonded to the tooth, The curing may beeffected in any desired manner of photopolymerization, chemicalpolymerization or dual curing of photo/chemical polymerization. In thiscase, however, the light, from the irradiator for photopolymerizationwill be often blocked by the prosthetic material. Therefore, for curingthe adhesive composition (end also the resin cement) in this case,preferred is chemical polymerization or dual curing polymerization.

In addition, the bonding compositions for dental use of the inventionmay also be combined with any other bonding ingredients of glass ionomercement, zinc phosphate cement, polycarboxylate cement, silicate cement,zinc oxide eugenol cement; and also with heat-curable resin,self-curable resin, root canal filler, or temporary sealant.

In particular, for repairing the restorative material having been brokenin the mouth, the adhesive compositions of the invention may be appliednot only to the tooth restored with the material but also to therepairing material of metals, ceramics or cured composite resins.Further, in their use, the bonding compositions of the invention may becombined with any commercially-available acid etchants or tooth surfacecleaners such as hypochlorites, etc.

EXAMPLES

The invention is described in more detail with reference to thefollowing Examples, which, however are not intended to restrict thescope of the invention. The meanings of the abbreviations usedhereinabove and also in the following Examples are mentioned below.

Abbreviations: Antibacterial Polymerizable Monomers: MDPB:methacryloyloxydodecylpyridinium bromide MHPC:methacryloyloxyhexedecylpyrodinium chloride HMPC:4-hexadecylmethacryloyloxyethylpyridinium chloride MHBP:methacryloyloxyethylhexadecylbipyridinium dichloride DMPC:methacryloyloxyoctadecyltrimethylphosphonium chloride OEPA:methacryloyloxyoctadecyltriethylphosphonium acetate MEDP:4-methacryloyloxyethyldodecylpyridinium chloride VHMS:di(4-vinylbenzyl)hexadecylmethylammonium methylsulfate DDMC:di(methacryloyloxyethyl)dodecylmethylammonium chloride BMPS:methacryloyloxyethyl(4-N-hexadecylpyridinylmethyl) succinate bromidePhotopolymerization Initiators: TMDPO:2,4,6-trimethylbenzoyldiphenylphosphine oxide DCOPO:2,6-dichlorobenzoyldiphenylphosphine oxide DEOPO:2,6-diethylbenzoyidiphenylphosphine oxide CQ: camphorquinone ReducingAgents, Oxidizing Agents: BSS: sodium benzenesulfinate TPBSS: sodium2,4,6-1-propylbenzenesulfinate DMAB: 4-dimethylaminobenzophenone DEPT:N,N-di(2-hydroxyethyl)-p-toluidine EDMABA: ethyl 4-dimethylaminobenzoateBPO: benzoyl peroxide Acid Group-Containing Polymerizable Monomers: MDP:10-methacryloyloxydecyl dihydrogenphosphate MUP:11-methacryloyloxyundecyl dihydrogenphosphate Polymerizable Polymers:Bis-GMA: bisphenol A diglycidyl dimethacrylate HEMA: 2-hydroxyethylmethacrylate HD: 1,6-hexanediol dimethacrylate DD: 1,10-dodecanedioldimethacrylate UDMA:[2,2,4-trimethylhexamethylenebis(2-carbamoyloxyethyl)] dimethacrylateTH: N,N′-(2,2,4-trimethylhexamethylene)bis[2-(aminocarboxy)propane-1,3-diol] tetramethacrylate PolymerizationInhibitor: BHT: t-butylhydroxytoluene

Example 1

Ethanol, distilled water and MDPB were mixed in a ratio by weight asindicated in Table 1 to prepare an antibacterial primer. MDP, distilledwater, HEMA, HD, CQ and DMAB were mixed in a ratio by weight asindicated in Table 1 to prepare an adhesive composition.

The antibacterial primer and the adhesive composition were tested forthe bonding strength, according to the bonding strength test methodmentioned below. The data obtained are shown in Table 1. In addition,these were tested for the antibacterial properties according to theantibacterial test methods mentioned below. The data obtained are shownin Table 1.

Bonding Strength Test Method

A bovine anterior tooth was polished in wet with #1000 Silicon CarbideAbrasive Paper (from Nippon Abrasive Paper) to make its surface smooth,then its enamel or dentin was exposed out, and water existing on itssurface was blown off with a dental air syringe. An adhesive tape(thickness: about 150 microns) with a hole having a diameter of 3 mm wasstuck on the surface of the exposed enamel or dentin. The antibacterialprimer of the invention to be tested was first applied to the holed areawith a brush, and the volatile solvent was dried up with a dental airsyringe. Next, the adhesive composition of the invention to be testedwas applied over it also with a brush, then left as such for 60 seconds,and thereafter blown with a dental air syringe to form a film having athickness of about 100 microns. Then, this was exposed to light for 30seconds and cured, for which used was a dental light emitter, Litel II(from Gunma Ushio Electric). Next, a commercially-available,photopolymerizable dental composite resin, Clearfill AP-X (from Kuraray)was put on it, covered with a film of Eval® (from Kuraray, film ofethylene/vinyl alcohol copolymer), and pressed against a glass slidesuperposed thereon. In that condition, this was exposed to light for 40seconds and cured, for which was used the same light emitter as above. Astainless steel rod having a diameter of 7 mm was attached to the curedsurface with a commercially-available dental resin cement, Panavia 21(from Kuraray) being disposed therebetween, and left as such for 30minutes. Eight test discs were prepared in all in that manner, and thesewere all immersed in water at 37° C. After having been thus immersedtherein for 24 hours, these were taken out and tested for the bondingstrength, for which was used a universal tester (from Instron). At across head speed of 2 mm/min, the tensile bonding strength of each testdisc was measured. The data of all test discs were averaged.

Antibacterial Test Method 1 (for Evaluating the Antibacterial Propertiesof Non-cured Discs)

A bovine anterior tooth was smoothly polished in wet with #1000 SiliconCarbide Abrasive Paper (from Nippon Abrasive Paper) to make its dentinexposed out, and cut into disks of 1 mm thick with a diamond saw. Anaqueous solution of 40% phosphoric acid was applied to both surfaces ofeach disc, and left as such for 60 seconds. Then, all discs were washedwith running water and thereafter kept in water while they were notused. The dentin surface of each disc was exposed out, and waterexisting thereon was blown off with a dental air syringe. On the otherhand, cells of Streptococcus mutans. IFO13955 which had beenpre-incubated for 24 hours in a liquid brain heart infusion (BHI) medium(from Nippon Pharmaceutical) were diluted with a germ-free physiologicalsaline solution to prepare a cell dilution having a cell concentrationof 1×10⁶ (CFU/ml), and 100 μl of this cell dilution was inoculated on aBHI-agar medium and uniformly spread thereover with a Conradi rod.

An adhesive tape with a hole having a diameter of 5 mm was stuck on thesurface of the dentin disc prepared previously, and the dentin disc withthe tape was put on the center of the agar medium prepared as above, andairtightly adhered thereto by gently pressing it. The antibacterialprimer of the invention to be tested was applied to the holed area ofthe tooth disc with a brush, and then the volatile solvent wasimmediately vaporized away with a dental air syringe. Next, the adhesivecomposition of the invention to be tested was applied thereto also witha brush, and left as such for 60 seconds. In that condition, theantibacterial primer and the adhesive composition penetrated into thetissue of the dentin disc. The dentin disc was then taken out of it, andthe BHI-agar medium was incubated at 37° C. for 48 hours. The growingcondition of the cells in the medium was observed, and the antibacterialproperties of the tested samples were evaluated according to thefollowing criteria:

++) The cells grew even in the area where the test disc was put, like inthe other area.

+) The cell growth was inhibited in the area where the test disc wasput, as compared with that in the other area.

−) No cell growth was found in the area where the test disc was put.

Antibacterial Test Method 2 (for Evaluating the Antibacterial Propertiesof Cured Discs)

An adhesive tape with a hole having an inner diameter of 9 mm was stuckon a film of Eval® (from Kuraray), and the film was fixed horizontallywith a metal doughnut (inner diameter: 15 mm, outer diameter: 40 mm,thickness: 0.5 mm) being put thereon. 10 μl of the antibacterial primerof the invention to be tested was dripped into the hole of the metaldoughnut, and the volatile solvent was immediately blown off with adental air syringe. Next, 10 μl of the adhesive composition of theinvention to tee tested was dripped thereinto, and cured throughexposure to light for 30 seconds with a dental light emitter, Litel II.Next. a commercially-available, photopolymerizable dental compositeresin, Clearfill AP-X (from Kuraray) was put on it, covered with a filmof Eval® (from Kuraray), and pressed against a glass slide superposedthereon. In that condition, this was exposed to light for 40 seconds andcured, for which was used the same light emitter as above. The cureddisc was released from the metal doughnut, and ultrasonically washedwith water for 1 hour.

Cells of Streptococcus mutans, IF013955 which had been pre-incubated for24 hours in a liquid brain heart infusion (BHI) medium (from NipponPharmaceutical) were diluted with a germ-free physiological salinesolution to prepare a cell dilution having a cell concentration of 1×10⁶(CFU/ml), and 100 μl of this cell dilution was inoculated on the cureddisc. After having left as such for 15 minutes, the cured disc was puton a BHI-agar medium with its cell dilution-coated surface facing themedium, and the cells were recovered from it. Further, the cured discwas put on the other site of the agar medium and pressed against it, andall remaining cells were recovered from it. Thus was prepared arecovered cell sample. On the other hand, 100 μl of the sell dilutionprepared previously was directly inoculated on a BHI-agar medium toprepare a control cell sample. Both samples were incubated at 37° C.first anaerobically for 24 hours and then aerobically for 24 hours, andthe number of colonies formed in each sample was counted. The cell deathpercentage on the cured disc was calculated according to the followingequation:

Cell Death Percentage $100 = {\frac{\begin{matrix}{{{number}\quad {of}\quad {colonies}\quad \left( {{in}\quad {control}} \right)} -} \\{{number}\quad {of}\quad {colonies}\quad \left( {{in}\quad {recovered}\quad {sample}} \right)}\end{matrix}}{{number}\quad {of}\quad {colonies}\quad \left( {{in}\quad {control}} \right)} \times}$

Examples 2 to 7

As in Table 1, various antibacterial primers were prepared in the samemanner as in Example 1, except that MDPB was not used but any of HMPC,MHBP, OEPA, VHMS, DDMC or BMPS was used in place of MDPB. The sameadhesive composition as in Example 1 was prepared. These antibacterialprimers and the adhesive composition were tested for the bondingstrength, according to the same bonding strength test method as inExample 1. The data obtained are shown in Table 1. In addition, thesewere tested for the antibacterial properties also according to the cameantibacterial test methods as in Example 1. The data obtained are shownin Table 1.

TABLE 1 Formulation (wt. pts) Antibacterial Bonding Example ExampleExample Example Example Example Example Composition 1 2 3 4 5 6 7Antibacterial Primer Ethanol 80 80 80 80 80 80 80 Distilled Water 20 2020 20 20 20 20 MDPB 1 − − − − − − HMPC − 1 − − − − − MHBP − − 1 − − − −OEPA − − − 1 − − − VHMS − − − − 1 − − DDMC − − − − − 1 − BMPS − − − − −− 1 Adhesive Composition MDP 50 50 50 50 50 50 50 Distilled Water 1 1 11 1 1 1 HEMA 40 40 40 40 40 40 40 HD 10 10 10 10 10 10 10 CQ 2 2 2 2 2 22 DMAB 2 2 2 2 2 2 2 Tensile Bonding Strength: after 24 hours at 37° C.(unit: MPa) Enamel 15.6 15.1 15.3 15.5 15.5 15.6 15.2 Dentin 13.2 13.413.3 13.7 13.1 13.3 13.2 Antibacterial Test 1 − − − − − − − (cell growthbelow non- cured disc) Antibacterial Test 2 100 100 100 100 100 100 100(cell death percentage (%) on cured disc)

Comparative Example 1

As in Table 2, a antibacterial primer was prepared in the same manner asin Example 1, except that MDPB was not used herein. The same adhesivecomposition as in Example 1 was prepared.

The antibacterial primer and the adhesive composition were tested forthe bonding strength, according to the same bonding strength test methodas in Example 1. The data obtained are shown in Table 2. In addition,these were tested for the antibacterial properties also according to thesame antibacterial test methods as in Example 1. The data obtained areshown in Table 2.

Comparative Example 2

As in Table 2, the same adhesive composition as in Example 1 wasprepared. The adhesive composition was used singly herein and tested forthe bonding strength, according to the same bonding strength test methodas in Example 1. The data obtained are shown in Table 2. In addition,this was used singly and tested for the antibacterial properties alsoaccording to the same antibacterial test methods as in Example 1. Thedata obtained are shown in Table 2.

Comparative Examples 3 to 9

As in Table 2, various adhesive compositions were prepared by adding anantibacterial polymerizable monomer of MDPB, HMPC, MHBP, OEPA, VHMS,DDMC OR BMPS was added to the adhesive composition of Example 1. Themeadhesive compositions were tested for the bonding strength, according tothe same bonding strength test method as in Example 1. The data obtainedare shown in Table 2. In addition, these were tested for theantibacterial properties also according to the same antibacterial testmethods as in Example 1. The data obtained are shown in Table 2.

TABLE 2 Formulation (wt. pts) Antibacterial Bonding Comp. Comp. Comp.Comp. Comp. Comp. Comp. Comp. Comp. Composition Ex. 1 Ex. 2 Ex. 3 Ex. 4Ex. 5 Ex. 6 Ex. 7 Ex. 8 Ex. 9 Antibacterial Primer Ethanol 80 DistilledWater 20 — — — — — — — — Adhesive Composition MDP 50 50 50 50 50 50 5050 50 Distilled Water  1  1  1  1  1  1  1  1  1 HEMA 40 40 40 40 40 4040 40 40 HD 10 10 10 10 10 10 10 10 10 CQ  2  2  2  2  2  2  2  2  2DMAB  2  2  2  2  2  2  2  2  2 MDPB − −  5 − − − − − − HMPC − − −  5 −− − − − MHBP − − − −  5 − − − − OEPA − − − − −  5 − − − VHMS − − − − − − 5 − − DDMC − − − − − − −  5 − BMPS − − − − − − − −  5 Tensile BondingStrength: after 24 hours at 37° C. (unit: MPa) Enamel   15.5   15.4  15.1   15.7   15.2   15.0   15.5   15.7   15.3 Dentin   13.1   13.2  13.0   12.7   13.1   13.3   13.2   13.4   13.1 Antibacterial Test 1 ++++ + + + + + + + (cell growth below non-cured disc) Antibacterial Test 2 0  0 58 60 59 66 68 61 64 (cell death percentage (%) on cured disc)

As in Table 1, the bonding compositions of Examples 1 to 7 (these arecomposed of an antibacterial primer comprising an antibacterialpolymerizable monomer and a volatile solvent, and an adhesivecomposition) all had a high bonding strength of about 15 MPa to thetooth enamel and about 13 MPa to the tooth dentin. In addition, thesecompletely killed the cells below their non-cured discs in theantibacterial test 1. The data in the test 1 support the strongantibacterial properties of the non-cured bonding compositions. In theantibacterial test 2, the cells adhered on the cured discs of thesebonding compositions were also completely killed. The data in the test 2support the strong antibacterial properties of the cured bondingcompositions.

However, as in Table 2, the non-cured and cured discs of thecompositions of Comparative Examples 1 and 2 (these do not contain anantibacterial polymerizable monomer) had no antibacterial properties,though their bonding strength was good.

On the other hand. the antibacterial properties of the non-cured andcured discs of the compositions of Comparative Examples 3 to 9 (thesecontain an antibacterial polymerizable monomer) were not enough to killthe cells around the discs, though the bonding strength of thecompositions was high, like that of the compositions of Examples 1 to 7.

Example 8

MDPB, ethanol, distilled water, TMDPO and BSS were mixed in a ratio byweight as indicated in Table 3 to prepare an antibacterial primer, MDP.HEMA, distilled water and TMDPO were mixed in a ratio by weight asindicated in Table 3 to prepare an adhesive primer. In addition, abonding agent was prepared from UDMA, HEMA, MDP, TMDPO, CQ, DMAB and asilane-processed quartz powder. These were tested for the tensilebonding strength to tooth, according to the bonding strength test methodmentioned below. The data obtained are shown in Table 3. In addition,these were tested for the antibacterial properties according to theantibacterial test methods mentioned below. The data obtained are shownin Table 3.

Bonding Strength Test Method

In the same manner as in the test method for Example 1 mentioned above,a bovine anterior tooth was polished to make its enamel or dentinexposed out, and water existing on its surface was blown off with adental air syringe. An adhesive tape (thickness: about 150 microns) witha hole having a diameter of 3 mm was stuck on the surface of the exposedenamel or dentin. The antibacterial primer of the invention to be testedwas first applied to the holed area with a brush, and the volatilesolvent was dried up with a dental air syringe. Next, the adhesiveprimer of the invention to be tested was applied over it also with abrush, and then left as such for 30 seconds, and its excessive part wasblown off with a dental air syringe. Next, the bonding agent to betested was further applied thereover also with a brush, and again blownwith a dental air syringe to form a film having a thickness of about 100microns. Then, this was exposed to light for 10 seconds and cured, forwhich used was a dental light emitter, Litel II. Next, like in Example1, a photopolymerizable dental composite resin, Clearfill AP-X (fromKuraray} was put on it, and cured thereon. Then, this was put in waterat 37° C. Eight test discs were prepared in all in that manner, andthese were all immersed in water at 37° C. After having been thusimmersed therein for 24 hours, these were taken out and tested for thetensile bonding strength. The data of all test discs were averaged.

Antibacterial Test Method 1 (for Evaluating the Antibacterial Propertiesof Non-cured Discs)

In the same manner as in Example 1, a bovine dentin disc was prepared.Also in the same manner as in Example 1, cells of Streptococcus mutans,IF013955 which had been pre-incubated for 24 hours in a liquid brainheart infusion (BHI) medium (from Nippon Pharmaceutical) were dilutedwith a germ-free physiological saline solution to prepare a celldilution having a cell concentration of 1×10⁶ (CFU/ml), and 100 μl ofthis cell dilution was inoculated on a BHI-agar medium and uniformlyspread thereover with a Conradi rod.

An adhesive tape with a hole having a diameter of 5 mm was stuck on thesurface of the dentin disc prepared previously, and the dentin disc withthe tape was put on the center of the agar medium prepared as above, andairtightly adhered thereto by gently pressing it. The antibacterialprimer of the invention to be tested was applied to the holed area ofthe dentin disc with a brush, and then the volatile solvent wasimmediately vaporized away with a dental air syringe. Next, the adhesiveprimer to be tested was applied thereto also with a brush, and left assuch for 30 seconds. After this, the bonding agent to be tested wasapplied thereover, and left as such for 30 seconds. In that condition,the antibacterial primer, the adhesive primer and the bonding agentpenetrated into the tissue of the dentin disc. The dentin disc was thentaken out of it, and the BHI-agar medium was incubated at 37° C. for 48hours. The growing condition of the cells in the medium was observed,and the antibacterial properties of the tested samples were evaluatedaccording to the same criteria as in Example 1.

Antibacterial Test Method 2 (for Evaluating the Antibacterial Propertiesof Cured Discs)

In the same manner as in Example 1, an adhesive tape with a hole havingan inner diameter of 9 mm was stuck on a film of Eval®, and the film wasfixed horizontally with a metal doughnut being put thereon. 10 μl of theantibacterial primer of the invention to be tested was dripped into thehole of the metal doughnut, and the volatile solvent was immediatelyblown off with a dental air syringe. Next, 10 μl of the adhesive primerof the invention to be tested was dripped thereinto, and blown with adental air syringe. Then, the bonding agent of the invention to betested was applied over this with a brush to form a film having athickness of about 100 μm. This was exposed to light for 10 seconds andcured, for which was used a dental light emitter, Litel II. Next, acommercially-available, photopolymerizable dental composite resin,Clearfill AP-X was put on it, covered with a film of Eval, and pressedagainst a glass slide superposed thereon. In that condition, this wasexposed to light for 40 seconds and cured, for which was used the samelight emitter as above. The cured disc was released from the metaldoughnut, and ultrasonically washed with water for 1 hour. The celldeath percentage on the discs prepared herein was obtained in the samemanner as in Example 1.

Example 9

DMPC, ethanol, distilled water, TMDPO and BSS were mixed in a ratio byweight as indicated in Table 3 to prepare an antibacterial primer. Onthe other hand, the same adhesive primer and bonding agent as in Example8 were prepared. These were tested for the bonding strength, accordingto the same bonding strength test method as in Example 8. The dataobtained are shown in Table 3. In addition, these were tested for theantibacterial properties also according to the same antibacterial testmethods as In Example 8. The data obtained are shown in Table 3.

Comparative Example 10

The same adhesive primer and bonding agent as in Example 8 wereprepared. These were tested for the bonding strength, according to thesame bonding strength test method as in Example 8. The date obtained areshown in Table 3. In addition, these were tested for the antibacterialproperties also according to the same antibacterial test methods as inExample 8. The data obtained are shown in Table 3.

Comparative Examples 11 and 12

As in Table 3, adhesive primers were prepared by adding any of MDPB orDMPC to the adhesive primer of Example 8. On the other hand, the samebonding agent as in Example 8 was prepared. Each adhesive primer wascombined the bonding agent and tested for the bonding strength,according to the same bonding strength test method as in Example 8. Thedata obtained are shown in Table 3. In addition, these were tested forthe antibacterial properties also according to the same antibacterialtest methods as in Example 8. The data obtained are shown in Table 3.

TABLE 3 Formulation (wt. pts) Antibacterial Bonding Exam- Exam- Comp.Comp. Comp. Composition ple 8 ple 9 Ex. 10 Ex. 11 Ex. 12 AntibacterialPrimer MDPB 1 − DMPC − 1 Ethanol 70 70 Distilled Water 30 30 — — — TMDPO0.2 0.2 BSS 1 1 Adhesive Composition Adhesive Primer MDP 10 10 10 10 10HEMA 40 40 40 40 40 Distilled Water 50 50 50 50 50 TMDPO 1 1 1 1 1 MDPB− − − 5 − DMPC − − − − 5 Bonding Agent UDMA 60 60 60 60 60 HEMA 35 35 3535 35 MOP 5 5 5 5 5 TMDPO 2 2 2 2 2 CQ 0.5 0.5 0.5 0.5 0.5 DMAB 0.5 0.50.5 0.5 0.5 Silane-processed 10 10 10 10 10 Quartz Powder TensileBonding Strength: after 24 hours at 37° C. (unit: MPa) Enamel 20.1 20.519.1 20.0 20.2 Dentin 19.3 19.5 19.2 18.9 19.1 Antibacterial Test 1 − −++ + + (cell growth below non-cured disc) Antibacterial Test 2 100 100 068 66 (cell death percentage (%) on cured disc)

As in Table 3, the bonding compositions of Examples 8 and 9 (these arecomposed of an antibacterial primer comprising an antibacterialpolymerizable monomer and a volatile solvent, and an adhesivecomposition) all had a high bonding strength of about 20 MPa to thetooth enamel and about 19 MPa to the tooth dentin. In addition, thesecompletely killed the cells below their non-cured discs in theantibacterial test 1. The data in the test 1 support the strongantibacterial properties of the non-cured bonding compositions. In theantibacterial test 2, the cells adhered on the cured discs of thesebonding compositions were also completely killed. The data in the test 2support the strong antibacterial properties of the cured bondingcompositions.

However, the non-cured and cured discs of the composition of ComparativeExample 10 (this does not contain an antibacterial polymerizablemonomer) had no antibacterial properties, though their bonding strengthwas good. On the other hand, the antibacterial properties of thenon-cured and cured discs of the compositions of Comparative Examples 11and 12 (in these, the adhesive primer contains an antibacterialpolymerizable monomer) were not enough to kill the cells around thediscs, though the bonding strength of the compositions was high, likethat of the antibacterial bonding compositions of Examples 8 and 9.

Example 10

MDPB and ethanol were mixed in a ratio by weight an indicated in Table 4to prepare an antibacterial primer. MDP, HEMA, distilled water, DEPT andCQ were mixed in a ratio by weight as indicated in Table 4 to prepare anadhesive primer. In addition, a bonding agent was prepared from Bis-GMA,HEMA, TMDPO, CQ and DMAB by mixing them in a ratio by weight asindicated in Table 4. These were tested for the tensile bonding strengthto tooth and for the antibacterial properties, according to the samebonding strength test method and the same antibacterial test methods asin Example 8. The data obtained are shown in Table 4.

Example 11

MDPB and ethanol were mixed in a ratio by weight as indicated in Table 4to prepare an antibacterial primer. MDP, HEMA, DEPT and CQ were mixed ina ratio by weight as indicated in Table 4 to prepare an adhesive primer.In addition, the same bonding agent an in Example 10 was prepared. Thesewere tested for the tensile bonding strength according to the samebonding strength test as in Example 8. The data obtained are shown inTable 4. In addition, these were tested for the antibacterial propertiesalso according to the same antibacterial test methods as in Example 8.The data obtained are shown in Table 4.

Comparative Example 13

The same adhesive primer and bonding agent as in Example 11 wereprepared. These were tested for the bonding strength, according to thesame bonding strength test method as in Example 8. The date obtained areshown in Table 4. In addition, these were tested for the antibacterialproperties also according to the same antibacterial test methods as inExample 8. The data obtained are shown in Table 4.

Comparative Examples 14 and 15

As in Table 4, adhesive primers were prepared by adding MDPB to any ofthe adhesive primers of Examples 10 and 11. On the other hand, the samebonding agent as in Example 10 was prepared. Each adhesive primer wascombined the bonding agent and tested for the bonding strength,according to the same bonding strength test method as in Example 8. Thedata obtained are shown in Table 4. In addition, these were tested forthe antibacterial properties also according to the same antibacterialtest methods as in Example 8. The data obtained are shown in Table 4.

TABLE 4 Formulation (wt. pts) Antibacterial Bonding Exam- Exam- Comp.Comp. Comp. Composition ple 10 ple 11 Ex. 13 Ex. 14 Ex. 15Anti-bacterial Primer MDPB 5 5 Ethanol 100 100 — — — AdhesiveComposition Adhesive Primer MDP 15 15 15 15 15 HEMA 60 80 80 60 80Distilled Water 25 − − 25 − MDPB − − − 5 5 DEPT 3 3 3 3 3 CQ 1 1 1 1 1Bonding Agent Bis-GMA 65 65 65 65 65 HEMA 35 35 35 35 35 TMDPO 3 3 3 3 3CQ 1 1 1 1 1 DMAB 1 1 1 1 1 Tensile Bonding Strength: after 24 hours at37° C. (unit: MPa) Enamel 20.7 16.8 16.6 20.1 16.5 Dentin 19.9 16.6 16.119.2 16.4 Antibacterial Test 1 − − ++ + + (cell growth below non-cureddisc) Antibacterial Test 2 100 100 0 65 64 (cell death percentage (%) oncured disc)

As in Table 4, the bonding compositions of Examples 10 and 11 (these arecomposed of an antibacterial primer comprising an antibacterialpolymerizable monomer and a volatile solvent, an adhesive primer, and abonding agent) all had a high bonding strength of about 16 to 20 MPa tothe tooth enamel and also to the tooth dentin. In addition, thesecompletely killed the cells below their non-cured discs in theantibacterial test 1. The data in the test 1 support the strongantibacterial properties of the non-cured bonding compositions. In theantibacterial test 2, the cells adhered on the cured discs of thesebonding compositions were also completely killed. The data in the test 2support the strong antibacterial properties of the cured bondingcompositions.

However, the non-cured and cured discs of the composition of ComparativeExample 13 (this does not contain an antibacterial polymerizablemonomer) had no antibacterial properties, though their bonding strengthwas good. On the other hand, the antibacterial properties of thenon-cured and cured discs of the compositions of Comparative Examples 14and 15 (in these, the adhesive primer contains an antibacterialpolymerizable monomer) were not enough to kill the cells around thediscs, though the bonding strength of the compositions was high, likethat of the compositions of Examples 10 and 11.

Example 12

MHPC and ethanol were mixed in a ratio by weight as indicated in Table 5to prepare an antibacterial primer. MDP, HEMA, distilled water, CQ, DMABand DEPT were mixed in a ratio by weighs as indicated in Table 5 toprepare an adhesive primer. In addition, TH, DD, MDP, TMDPO, BPO andsilane-processed quartz powder were mixed in a ratio by weight asindicated in Table 5 to prepare a resin cement (A); and TH, HEMA, DD,DEPT, TPBSS and silane-processed quartz powder were mixed in a ratio byweight as indicated in Table 5 to prepare a resin cement (B). These weretested for the bonding strength to tooth, according to the bondingstrength test method mentioned below. In addition, these were tested forthe antibacterial properties according to the antibacterial test methodsmentioned below.

Bonding Strength Test Method

In the same manner as in the test method for Example 1 mentioned above,a bovine anterior tooth was polished to make its enamel or dentinexposed out, and water existing on its surface was blown off with adental air syringe. An adhesive tape (thickness: about 150 microns) witha hole having a diameter of 5 mm was stuck on the surface of the exposedenamel or dentin. The antibacterial primer of the invention to be testedwas first applied to the holed area with a brush, and the volatilesolvent was dried up with a dental air syringe. Next, the adhesiveprimer of the invention to be tested was applied over it also with abrush, and then left as such for 30 seconds, and its excessive part wasblown off with a dental air syringe.

Next, the resin cement (A) and the resin cement (B) of the invention tobe tested were mixed in ratio of 1/1 to prepare a paste, and the pastewas applied to a stainless steel rod having a diameter of 7 mm. This waspressed against the adhesive primer-coated surface of the tooth havingbeen treated as above. After left as such for 30 minutes, this wasimmersed in water at 37° C. After having been thus immersed therein for24 hours, this was taken out and its tensile bonding strength wasmeasured.

Antibacterial Test Method 1 (for Evaluating the Antibacterial Propertiesof Non-cured Discs)

In the same manner as in Example 1, a bovine dentin disc was prepared.Also in the same manner as in Example 1, cells of Streptococcus mutans,IF013955 which had been pre-incubated for 24 hours in a liquid brainheart infusion (BHI) medium (from Nippon Pharmaceutical) were dilutedwith a germ-free physiological saline solution to prepare a celldilution having a cell concentration of 1×10⁶ (CFU/ml), and 100 μl ofthis cell dilution was inoculated on a BHI-agar medium and uniformlyspread thereover with a Conradi rod.

An adhesive tape with a hole having a diameter of 5 mm was stuck on thesurface of the dentin disc prepared previously (thickness: 1 mm), andthe dentin disc with the tape was put on the center of the BHI-agarmedium prepared as above, and airtightly adhered thereto. Theantibacterial primer of the invention to be tested was applied to theholed area of the tooth disc with a brush, and then the volatile solventwas immediately vaporized away with a dental air syringe. Next, theadhesive primer to be tested was applied thereto also with a brush, andleft as such for 30 seconds. In that condition, the antibacterial primerand the adhesive primer penetrated into the tissue of the dentin disc.The dentin disc was then taken out of it, and the agar medium wasincubated at 37° C. for 48 hours. The growing condition of the cells inthe medium was observed, and the antibacterial properties of the testedsamples were evaluated according to the same criteria as in Example 1.

Antibacterial Test Method 2 (for Evaluating the Antibacterial Propertiesof Cured Discs)

In the same manner as in Example 1, an adhesive tape with a hole havingan inner diameter of 9 mm was stuck on a film of Eval, and the film wasfixed horizontally with a metal doughnut being put thereon. 10 μl of theantibacterial primer of the invention to be tested was dripped into thehole of the metal doughnut, and the volatile solvent was immediatelyblown off with a dental air syringe. Next, 10 μl of the adhesive primerof the invention to be tested was dripped thereinto, and blown with adental air syringe. Then, a paste of the resin cement (A) and the resincement (B) of the invention to be tested, as prepared by mixing them ina ratio of 1/1, was applied over this, covered with an Eval film, andpressed against a glass slide superposed thereon. In that condition,this was left as such for 60 minutes and cured. The cured disc wasreleased from the metal doughnut, and ultrasonically washed with waterfor 1 hour. The cell death percentage on the discs prepared herein wasobtained in the same manner as in Example 1.

Example 13

MEDP and ethanol were mixed in a ratio by weight as indicated in Table 5to prepare an antibacterial primer. On the other hand, the same adhesiveprimers resin cement (A) and resin cement (B) as in Example 12 wereprepared. These were tested for the bonding strength, according to thesame bonding strength test method as in Example 12. The data obtainedare shown in Table 5. In addition, these were tested for theantibacterial properties also according to the same antibacterial testmethods as in Example 12. The data obtained are shown in Table 5.

Comparative Example 16

The same adhesive primer, resin cement (A) and resin cement (B) as inExample 12 were prepared. These were tested for the bonding strength,according to the same bonding strength test method as in Example 12. Thedata obtained are shown in Table 5. In addition, these were tested forthe antibacterial properties also according to the same antibacterialtest methods as in Example 12. The data obtained are shown in Table 5.

Comparative Examples 17 and 18

As in Table 5, adhesive primers were prepared by adding any of MHPC orMEDP to the adhesive primer of Example 12. On the other hand, the sameresin cement (A) and resin cement (B) as in Example 12 was prepared.There were combined and tested for the bonding strength, according tothe same bonding strength test method as in Example 12. The dataobtained are shown in Table 5. In addition, these were tested for theantibacterial properties also according to the same antibacterial testmethods as in Example 12. The data obtained are shown in Table 5.

TABLE 5 Formulation (wt. pts) Antibacterial Bonding Exam- Exam- Comp.Comp. Comp. Composition ple 12 ple 13 Ex. 16 Ex. 17 Ex. 18 AntibacterialPrimer MHPC 1 − MEDP − 1 — — — Ethanol 100 100 Adhesive CompositionAdhesive Primer MDP 10 10 10 10 10 HEMA 40 40 40 40 40 Distilled Water50 50 50 50 50 CQ 0.5 0.5 0.5 0.5 0.5 DMAB 1 1 1 1 1 DEPT 5 5 5 5 5 MHPC− − − 5 − MEDP − − − − 5 Resin Cement A TH 60 60 60 60 60 DD 5 5 5 5 5MDP 30 30 30 30 30 TMDPO 2 2 2 2 2 BPO 2 2 2 2 2 Silane-processed 300300 300 300 300 Quartz Powder B TH 70 70 70 70 70 HEMA 20 20 20 20 20 DD10 10 10 10 10 DEPT 1 1 1 1 1 TPBSS 1 1 1 1 1 Silane-processed 300 300300 300 300 Quartz Powder Tensile Bonding Strength: after 24 hours at37° C. (unit: MPa) Enamel 20.5 20.0 20.3 20.2 20.0 Dentin 13.4 13.3 13.112.6 12.3 Antibacterial Test 1 − − ++ + + (cell growth below non-cureddisc) Antibacterial Test 2 100 100 0 61 63 (cell death percentage (%) oncured disc)

As in Table 5, the bonding compositions of Examples 12 and 13 (these arecomposed of an antibacterial primer comprising an antibacterialpolymerizable monomer and a volatile solvent, an adhesive primer, aresin cement (A), and a resin cement(B) all had a high bonding strengthof about 20 MPa to the tooth enamel and about 13 MPa to the toothdentin. In addition, these completely killed the cells below theirnon-cured discs in the antibacterial test 1. The data in the test 1support the strong antibacterial properties of the non-cured bondingcompositions. In the antibacterial test 2, the cells adhered on thecured discs of these bonding compositions were also completely killed.The data in the test 2 support the strong antibacterial properties ofthe cured bonding compositions.

However, the non-cured and cured discs of the composition of ComparativeExample 16 (this does not contain an antibacterial polymerizablemonomer) had no antibacterial properties, though their bonding strengthwas good. On the other hand, the antibacterial properties of thenon-cured and cured discs of the compositions of Comparative Examples 17and 18 (in these, the adhesive primer contains an antibacterialpolymerizable monomer) were not enough to kill the cells around thediscs, though the bonding strength of the compositions was high, likethat of the compositions of Examples 12 and 13.

Example 14

MUP, HEMA and distilled water were mixed in a ratio by weight asindicated in Table 6 to prepare an adhesive primer. On the other hand,UDMA, HEMA, TMDPO, CQ, EDMABA and DEPT were mixed in a ratio by weightas indicated in Table 6 to prepare a bonding agent.

The adhesive primer and the bonding agent were tested according to thephoto-curing test methods mentioned below, in which the photo-curingtime and the photo-cured depth were measured. The data obtained areshown in Table 6. In addition, these were tested for the bondingstrength according to the same bonding strength test as in Example 8.Further, these were subjected to a bonding curability test, in which thebonded discs to be tested were exposed to 10000 heat cycles (one cyclecomprises immersing the bonded discs in water at 37° C. for 24 hours,then in cold water at 4° C. and hot water at 60° C. for 1 minute each),and their bonding strength was measured. The data obtained are also inTable 6.

Method for Measuring Photo-curing Time (1)

A bovine anterior sooth was smoothly polished in wet with #1000 SiliconCarbide Abrasive Paper (from Nippon Abrasive Paper) to make its dentinexposed out, and water existing on its surface was blown off with adental air syringe. The adhesive primer to be tested was applied to theexposed dentin surface with a brush, then left as such for 30 seconds,and thereafter dried with an air syringe. Next, a washer with a holehaving a depth of 0.8 mm and a diameter of 4 mm was put on it, and thehole was filled with the bonding agent to be tested. With the tip of athermocouple being inserted into the hole in that condition, the samplewas exposed to light, for which used was a dental light emitter, LitelII (from Gunma Ushio Electric). During the exposure, the temperaturechange in the sample was recorded through the thermocouple, from whichwas obtained the time from the start of the exposure to the heat peak.The time indicates the photo-curing time for the sample.

Method for Measuring Photo-cured Depth (2)

A mold having a diameter of 4 mm and a depth of 5 mm was filled with thebonding agent to be tested, and exposed to light for 10 seconds from adental light emitter, Litel (from Gunma Ushio Electric). Then, the discsample was released from the mold, and the non-cured bonding agent waswiped away with tissue paper. The cured sample which was still soft wascompressed under a load of 500 g, and its thickness was measured with avernier micrometer.

Examples 15 to 17 and Comparative Examples 19 to 22

The same adhesive primer as in Example 14 and as in Table 6 wasprepared. In addition, bonding agents were prepared by mixing UDMA orBis-GMA, and any of HD, HEMA, TMDPO, DCDPO, CQ, EDMABA and DEPT in aratio by weigh as indicated in Table 6.

The adhesive primer and the bonding agents were tested for thephoto-curing time, the photo-cured depth and the bonding strength,according to the same photo-curing tests and bonding strength tests asin Example 14. The data obtained are shown in Table 6.

TABLE 6 Formulation (wt. pts) Comp. Comp. Comp. Comp. AdhesiveComposition Ex. 14 Ex. 15 Ex. 16 Ex. 17 Ex. 19 Ex. 20 Ex. 21 Ex. 22Adhesive Primer MUP 20 20 20 20 20 20 20 20 HEMA 40 40 40 40 40 40 40 40Distilled Water 40 40 40 40 40 40 40 40 Bonding Agent UDMA 70 70 − − 70− 70 − Bis-GMA − − 45 45 − 45 − 45 HD − − 20 20 − 20 − 20 HEMA 30 30 3535 30 35 30 35 TMDPO 2.5 − 2.5 − 2.8 2.8 − − DCDPO − 2.5 − 2.5 − − − −CQ 0.3 0.3 0.3 0.3 − − 2.8 2.8 EDMABA 1 1 1 1 1 1 1 1 DEPT 0.5 0.5 0.50.5 0.5 0.5 0.5 0.5 Photo-curing Time (sec) 8.2 8.4 8.2 8.2 9.8 9.7 14.814.2 Photo-cured Depth (mm) 2.0 2.1 2.0 1.9 0.5 0.4 1.1 1.0 TensileBonding Strength (unit: MPa) After 24 hours at 37° C. Enamel 20.1 20.320.4 20.2 19.7 19.6 18.1 19.8 Dentin 19.0 18.8 18.7 21.3 19.3 19.1 16.216.8 After Heat Cycle Test Enamel 21.2 21.0 20.3 19.5 12.1 12.5 6.8 6.7Dentin 17.6 17.5 17.9 18.3 11.5 11.6 5.8 5.9

As in Table 6, it is understood that the adhesive compositions ofExamples 14 to 17 (in these, the bonding agent comprises anacylphosphine oxide compound and CQ both serving as aphotopolymerization initiator) cured within a period of 10 seconds, andthat their photo-cured depth reached about 2 mm after exposure for 10seconds. The data support the good photocurability of the compositions.In addition, in the heat cycle test for the bonding durability, thebonding strength of the compositions decreased little after heat cycles.However, the adhesive compositions of Comparative Examples 19 and 20 (inthese, the bonding agent comprises TMDPO only as the photopolymerizationinitiator) had a photo-cured depth of about 0.5 mm even though theycured within 10 seconds. The data indicate that the photocurability ofthese comparative compositions is not satisfactory. In addition, thebonding strength of the comparative compositions lowered after heatcycles. On the other hand, the adhesive compositions of ComparativeExamples 21 and 22 (in these, the bonding agent comprises CQ only as thephotopolymerization initiator) could not be completely cured within 10seconds, and their photo-cured depth was only 1 mm or so. The dataindicate that the photocurability of these comparative compositions isnot good. In addition the bonding strength of the comparativecompositions noticeably lowered after heat cycles.

Examples 18 to 21 and Comparative Examples 23 to 26

MDP, HEMA, CQ, DMAB and distilled water were mixed in a ratio by weightas indicated in Table 7 to prepare adhesive primers. On the other hand,bonding agents were prepared by mixing UDMA or Bis-GMA, and any of HD,HEMA. MDP, TMDPO, DEDPO, CQ, EDMABA and BHT in a ratio by weigh asindicated in Table 7.

The adhesive primer and the bonding agents were tested for thephoto-curing time, the photo-cured depth and the bonding strength,according to the same photo-curing tests and bonding strength tests asin Example 14. The data obtained are shown in Table 7.

TABLE 7 Formulation (wt. pts) Comp. Comp. Comp. Comp. AdhesiveComposition Ex. 18 Ex. 19 Ex. 20 Ex. 21 Ex. 23 Ex. 24 Ex. 25 Ex. 26Adhesive Primer MDP 15 15 15 15 15 15 15 15 HEMA 40 40 40 40 40 40 40 40CQ 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 DMAB 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5Distilled Water 45 45 45 45 45 45 45 45 Bonding Agent UDMA 65 65 − − 65− 65 − Bis-GMA − − 40 40 − 40 − 40 HD − − 25 25 − 25 − 25 HEMA 30 30 3030 30 30 30 30 MDP 5 5 5 5 5 5 5 5 TMDPO 2.5 − 2.5 − 2.8 2.8 − − DEDPO −2.5 − 2.5 − − − − CQ 0.3 0.3 0.3 0.3 − − 2.8 2.8 EDMABA 1 1 1 1 1 1 1 1BHT 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 Photo-curing Time (sec) 8.28.4 8.3 8.4 9.9 9.8 13.5 13.6 Photo-cured Depth (mm) 2.2 2.1 2.1 2.2 0.50.5 1.6 1.6 Tensile Bonding Strength (unit: MPa) After 24 hours at 37°C. Enamel 22.3 22.5 22.6 22.4 21.9 21.8 19.4 18.9 Dentin 21.2 21.9 21.822.1 19.8 19.7 17.5 17.4 After Heat Cycle Test Enamel 22.1 21.6 21.121.3 13.7 13.8 8.7 8.6 Dentin 20.6 20.8 19.7 20.5 13.8 13.9 8.8 8.6

As in Table 7, it is understood that the adhesive compositions ofExamples 18 to 21 (in these, the bonding agent comprises anacylphosphine oxide compound and CQ both serving as aphotopolymerization initiator) cured within a period of 10 seconds, andthat their photo-cured depth reached about 2 mm after exposure for 10seconds. The data support the good photocurability of the compositions.In addition, in the heat cycle test for the bonding durability, thebonding strength of the compositions decreased little after heat cycles.However, the adhesive compositions of Comparative Examples 23 and 24 (inthese, the bonding agent comprises TMDPO only as the photopolymerizationinitiator) had a photo-cured depth of about 0.5 mm even though theycured within 10 seconds. The data indicate that the photocurability ofthese comparative compositions is not satisfactory. In addition, thebonding strength of the comparative compositions lowered after heatcycles. On the other hand, the adhesive compositions of ComparativeExamples 25 and 26 (in these, the bonding agent comprises CQ only as thephotopolymerization initiator) could not be completely cured within 10seconds, and their photo-cured depth was only 1.5 mm or so. The dataindicate that the photocurability of these comparative compositions isnot good. In addition, the bonding strength of the comparativecompositions noticeably lowered after heat cycles.

Examples 22 to 26 and Comparative Examples 27 to 29

The adhesive primer of Example 20 was again prepared herein. On theother hand, different bonding agents were prepared in the same manner asin Example 20 except that the proportions of TDMPO and CQ both servingas a photopolymerization initiator were varied. The adhesive primer andthe bonding agents were tested for the bonding strength, according tothe same bonding strength tests as in Example 14. The data obtained areshown in Table 8. In addition, the bonding agents were tested for thelight stability according to the light stability test mentioned below.The data obtained are shown in Table 8.

Light Stability Test

A sampling dish was put on a laboratory table, and a fluorescent lampwith a movable stand was so fitted thereto that the illuminance at thedish could be 1,000 luxes. 0.03 g of the bonding agent to be tested wasput into the dish, and exposed to the fluorescent lamp under thatcondition. The time before a part of the bonding agent in the dish curedor gelled was measured.

TABLE 8 Comp. Comp. Comp. Ex. 22 Ex. 23 Ex. 24 Ex. 25 Ex. 26 Ex. 27 Ex.28 Ex. 29 TMDPO (wt. pts.) 5 3 3 3 3 3 3 3 CQ (wt. pts.) 0.05 0.1 0.3 11.5 − 3 4 Ratio for Formulation 0.01 0.03 0.10 0.33 0.50 0.00 1.00 1.33dQ/TMDPO Tensile Bonding Strength (unit: MPa) After 24 hours at 37° C.Enamel 22.3 22.0 22.5 22.3 22.1 20.8 21.4 22.9 Dentin 20.2 20.3 20.720.1 20.5 19.8 19.7 19.4 After Heat Cycle Test Enamel 22.1 21.8 21.521.8 21.7 13.8 20.7 21.6 Dentin 20.4 20.7 20.7 20.4 21.0 13.9 19.8 20.6Light Stability (1000 luxes) Time before Gelling >3 min. >3 min. >3min. >3 min. >3 min. >3 min. 2 min. 2 min. and 30 and 10 sec sec

As in Table 8, the bonding agents where the ratio of TMDPO to CQ fallsbetween 1:0.01 and 1:0.5 had excellent bonding durability to tooth. Fortheir light stability, the bonding agents did not gel after exposed tolight of 1000 luxes for 3 minutes or longer (Examples 22 to 26).However, the bonding agent not containing CQ had poor bondingdurability, though its light stability was good (Comparative Example27). The bonding agents where the ratio of TMDPO:CQ is 1:1 (ComparativeExample 28) or 1:1.33 (Comparative Example 29) gelled after exposed tolight of 1000 luxes within 3 minutes, though their bonding strength washigh. The data indicate that the light stability of these comparativecomponents is poor.

As described hereinabove, the bonding compositions for dental use of thepresent invention can firmly bond a tooth and a restorative dentalmaterial applied thereto, and, in addition, can kill bacteria remainingin the fine structure of the bonded interface such as toothal canals,etc. Moreover, they can kill bacteria that may penetrate into the bondedinterface, and are therefore effective for preventing secondary cariesand infectious odontitis.

In the adhesive compositions for dental use of the invention comprisinga primer and a bonding agent, the bonding agent comprises anacylphosphine oxide compound and an α-diketone compound both serving asa photopolymerization initiator. In these, not only the bonding agentbut also the adhesive primer can be firmly photo-cured at the same timewithin a short period of time, and the bonding durability of thecompositions to the tooth is significantly increased.

Obviously, numerous modifications and variations of the presentinvention are possible in light of the above teachings. It is thereforeto be understood that within the scope of the appended claims, theinvention may be practiced otherwise than as specifically describedherein.

This application is based on Japanese Patent Application Serial No. JP10-233777, filed on Aug. 20, 1998, and Japanese Patent ApplicationSerial No. JP 11-17826, filed on Jan. 27, 1999, both of which areincorporated herein by reference in their entirety.

What is claimed is:
 1. An adhesive composition, comprising: (P) anadhesive primer comprising (i) a polymerizable monomer containing anacid group, (ii) a hydrophilic polymerizable monomer, and (iii) water;and (Q) a bonding agent comprising (i) a polymerizable monomer, (ii) anacylphosphine oxide compound, and (iii) an α-diketone compound; whereinthe ratio of the acylphosphine oxide compound to the α-diketone compoundis 1:0.01 to 1:0.5 and the total amount of the acylphosphine oxidecompound and the α-diketone compound in the bonding agent is between 1%by weight and 6% by weight.
 2. The adhesive composition of claim 1,wherein said bonding agent (Q) further comprises a polymerizable monomercontaining an acid group.
 3. The adhesive composition of claim 1,wherein said adhesive primer (P) further comprises a polymerizationinitiator.
 4. The adhesive composition of claim 1, wherein thepolymerizable monomer (i) of said adhesive primer (P) comprises an acidgroup comprising phosphoric acid, pyrophosphoric acid, thiophosphoricacid, carboxylic acid, or sulfonic acid.
 5. The adhesive composition ofclaim 4, wherein said polymerizable monomer (i) of said adhesive primer(P) comprises 0.1 to 80% by wt. of said adhesive primer (P).
 6. Theadhesive composition of claim 1, wherein the acylphosphine oxidecompound (ii) of the bonding agent (Q) comprises2,4,6-trimethylbenzoyldiphenylphosphine oxide,2,6-diethylbenzoyldiphenylphosphine oxide,2,6-dimethoxybenzoyldiphenylphosphine oxide,2,6-dichlorobenzoyldiphenylphosphine oxide,2,3,5,6-tetramethylbenzoyldiphenylphosphine oxide,benzoyldi-(2,6-dimethylphenyl)phosphonate,2,4,6-trimethylbenzoylethoxyphenylphosphine oxide or water-solubleacylphosphine oxides.
 7. The adhesive composition of claim 1, whereinsaid α-diketone compound (iii) of said bonding agent (Q) comprisescamphorquinone, benzil or 2,3-pentanedione.
 8. The adhesive compositionof claim 1, wherein said bonding agent (Q) further comprises a reducingagent in an amount of about 0.5 to 10% by wt. based on the total weightof the bonding agent.
 9. The adhesive composition of claim 8, whereinsaid reducing agent comprises amines, aldehydes, mercaptans or salts ofsulfinic acids.
 10. The adhesive composition of claim 1, whereinaccording to a light stability test, when 0.03 g of said bonding agentis exposed to a fluorescent lamp at an illuminance of 1,000 luxes, thetime before a part of the bonding agent is cured or gelled is greaterthan 3 minutes.